What is a good woba in mlb?

Reaching base is the most important thing a batter can do in baseball. Getting on base more often equates to scoring more runs and ultimately winning more games. But, some methods of reaching base are more effective than others in scoring runs, which is what wOBA measures.

So, what is wOBA in baseball?

Weighted on-base average, or wOBA, measures how often a player reaches base and how they reach base. Hits that produce more runs, like home runs, have the highest weight in calculating wOBA. Hit by pitches and walks have the lowest weight since they are less likely to score runs as a result.

This article explains what wOBA is and how it compares to other stats like OBA and OPS. It also explains what a good and bad wOBA is and covers the all-time wOBA leaders. Lastly, we’ll go into detail on xwOBA and decide if wOBA is a good stat.

wOBA is a stat in baseball used to measure how often a player reaches base and how likely they are to score runs as a result of reaching base.

Here is the MLB’s definition of wOBA:

wOBA is a version of on-base percentage that accounts for how a player reached base — instead of simply considering whether a player reached base. The value for each method of reaching base is determined by how much that event is worth in relation to projected runs scored (example: a double is worth more than a single).

For instance: In 2014, a home run was worth 2.101 times on base, while a walk was worth 0.69 times on base. So a player who went 1-for-4 with a home run and a walk would have a wOBA of .558 — (2.101 + 0.69 / 5 PAs).

As you can see in the formula above, home runs are weighted significantly higher than walks in the wOBA formula. The other ways of getting on base (hit by pitch, singles, doubles, and triples) all weigh between a walk and a home run.

So, wOBA gives more weight to hits that give you multiple bases and are more likely to produce runs. The more bases you get on hits, the higher your wOBA.

On-base average, also called OBA or on-base percentage, is similar to wOBA, but every method of reaching base has the same value in calculating the stat. So a home run, a single, and a walk count the same.

Here is the MLB’s official definition of OBA:

OBP refers to how frequently a batter reaches base per plate appearance. Times on base include hits, walks and hit-by-pitches, but do not include errors, times reached on a fielder’s choice or a dropped third strike. (Separately, sacrifice bunts are removed from the equation entirely, because it is rarely a hitter’s decision to sacrifice himself, but rather a manager’s choice as part of an in-game strategy.)

A hitter’s goal is to avoid making an out, and on-base percentage shows which hitters have accomplished that task the best.

On-base percentage can also be applied as an evaluative tool for pitchers, although this is done less frequently. In such cases, it is referred to as on-base against.

OBA and wOBA both determine how often a player reaches base. But with OBA, it doesn’t matter if you have a walk, a single, or a home run. All methods of getting on base give you the same OBA.

wOBA measures how good a player is offensively. The higher the wOBA, the better a player is at reaching base and producing runs as a result of reaching base.

The more multi-base hits a player has, the higher their wOBA will be. The reason is that multi-base hits (doubles, triples, and home runs) have the highest weight when calculating wOBA.

So, a higher wOBA means a player is getting more home runs, triples, and doubles and likely produces more runs for each hit.

And, an average wOBA doesn’t mean a player is not as good offensively, but that they are hitting more singles or walking more than they are getting multi-base hits.

A low wOBA means the player is either not reaching base as often as they should or getting a lot of walks to get them on base. With many walks, they are still getting on base, but them getting on base is not producing runs. Since walks are weighted lowest in the wOBA formula, more walks mean a lower wOBA.

You may wonder why walks and hit by pitches have a lower weight than singles when all of them only get the batter one base. Well, wOBA also measures how effective each way of reaching base is at scoring runs.

While all three of these only get the batter to first base, other players can still score on each one. For a run to score on a walk or hit by pitch, the bases have to be loaded, and the runner at third will score. But, on a single, up to three runs can score if the bases are loaded since the runners aren’t limited to only one base.

The formula for calculating wOBA is always the same, but some of the numbers within the equation, called factors, change each year.

Here is the MLB’s official formula for wOBA:

Where “factor” indicates the adjusted run expectancy of a batting event in the context of the season as a whole: (unintentional BB factor x unintentional BB + HBP factor x HBP + 1B factor x 1B + 2B factor x 2B + 3B factor x 3B + HR factor x HR)/(AB + unintentional BB + SF + HBP).

The “factor” in the MLB’s formula above changes every year based on the expected number of runs for each event compared to an out. Home runs have the highest factor since they produce the highest number of runs for each home run. Walks have the lowest factor since they have the lowest number of runs as a result of each walk.

First, here’s the general wOBA formula. Each F stands for the factor for the specific scoring method it’s being multiplied by.

wOBA = (F * Non-intentional Walks + F * Hit by Pitch + F * Singles + F * Doubles + F * Triples + F * Home Runs) / (At Bats + Walks + Intentional Walks + Sacrifice Flies + Hit by Pitch)

Now, let’s look at the wOBA formula for the 2021 season, with each specific factor for getting on base. Below are the factors for each method:

Home Runs = 2.007

2021 wOBA = (0.692 * Non-intentional Walks + 0.722 * Hit by Pitch + 0.879 * Singles + 1.242 * Doubles + 1.568 * Triples + 2.007 * Home Runs) / (At Bats + Walks + Intentional Walks + Sacrifice Flies + Hit by Pitch)

The average wOBA in MLB changes every year, but the average wOBA is generally around 0.320. So, a good wOBA is anything above .320, and the higher, the better.

The best offensive players have wOBAs over 0.400. As we detail later in the article, the players with the highest wOBAs in MLB for the 2021 season and career leaders all have wOBAs over 0.400.

A bad wOBA is less than the average of 0.320, and the lower it is, the worse the player is at reaching base and helping their team score runs. The worst wOBAs are 0.300 or lower, and players with wOBAs around these numbers aren’t good offensive players. They are bad at reaching base and producing runs.

wOBA is a good stat because it measures how often a player reaches base and how that player reaches base.

wOBA is important because it gives a different value to each way to reach on base, so certain methods have more weight and, therefore, more impact on a player’s wOBA. Home runs have the highest wOBA value, so the more home runs a player has, the higher their wOBA.

Comparing wOBAs between players and teams is one of the best stats to determine how efficient a team or player is at reaching base for each at bat they have. Higher wOBAs mean players are getting more bases per at bat, leading to more runs.

wOBA and OPS both measure how effective a batter is at reaching base. But, wOBA is better than OPS because it’s a more accurate measurement since it considers how the batter reaches the base.

Career wOBA includes all walks, hit by pitches, hits, and plate appearances throughout a player’s entire career in MLB.

Here are the MLB Career wOBA leaders from Stat Muse:

A player’s season wOBA takes all their hits, walks, hit by pitches, and plate appearances for an entire season.

Here are the 2021 MLB wOBA leaders per Baseball Savant:

Expected weighted on-base average, or xwOBA is the projected wOBA for a player. But it doesn’t always end up being the wOBA that a player ends up with for the season. And, the actual wOBA can be higher or lower than the xwOBA.

The xwOBA is projected based on the exit velocity, the launch angle, and the sprint speed of hit balls by a player. Calculating xwOBA started in 2015 thanks to Statcast.

Here is MLB’s official definition of xwOBA:

Expected Weighted On-base Average (xwOBA) is formulated using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed.

In the same way that each batted ball is assigned an expected batting average, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls since Statcast was implemented Major League wide in 2015. For the majority of batted balls, this is achieved using only exit velocity and launch angle. As of 2019, “topped” or “weakly hit” balls also incorporate a batter’s seasonal Sprint Speed.

Knowing the expected outcomes of each individual batted ball from a particular player over the course of a season — with a player’s real-world data used for factors such as walks, strikeouts and times hit by a pitch — allows for the formation of said player’s xwOBA based on the quality of contact, instead of the actual outcomes. Likewise, this exercise can be done for pitchers to get their expected xwOBA against.

While xwOBA and wOBA may seem like the same stat, they are different because xwOBA doesn’t have any defensive factors.

For example, suppose a player hits a ball that should be a double based on velocity and launch angle, but the center fielder makes an impressive play to catch the ball. wOBA wouldn’t include this in its calculation except for being included as an at-bat. But, xwOBA would include the hit as a double in its calculation since it’s based on the player’s ability to hit and ignores defense.

Here is the MLB’s formula for calculating xwOBA:

All hit types are valued in the same fashion for xwOBA as they are in the formula for standard wOBA: (unintentional BB factor x unintentional BB + HBP factor x HBP + 1B factor x 1B + 2B factor x 2B + 3B factor x 3B + HR factor x HR)/(AB + unintentional BB + SF + HBP), where “factor” indicates the adjusted run expectancy of a batting event in the context of the season as a whole. The factors used in calculating xwOBA are the same ones used in the wOBA formula.

OPS (on-base plus slugging) and wOBA are stats that determine how good a player is at reaching base. As we know, wOBA considers how often a player gets on base, and how they got there.

On the other hand, OPS doesn’t consider how they got on base. OPS is a measurement of on-base percentage and slugging percentage. When calculating OPS, the different types of hits aren’t weighted like they are when calculating wOBA.

OPS does consider extra-base hits since it includes slugging percentage, which calculates how many extra-base hits a batter has. But, it only considers the number of bases per hit, not by any weighted factors for how many runs scored as wOBA does.

Both wOBA and OBA measure how good a player is at reaching base. But, wOBA gives more weight to different hits depending on how many runs are scored on average as a result of each hit.

OBA only considers how often a player reaches base per the number of at bats they have and not how many bases they got on each hit. So, unlike wOBA, a walk, a hit by pitch, a single, a double, a triple, and a home run all have the same weight in calculating OBA.

So, suppose two players both have five at bats in a game with no walks, hit by pitches, or sacrifice flies. One player has three home runs, and the other has three singles. Both players would have the same OBA of 0.600 for the game.

Reaching base is the most important thing a batter can do in baseball. Getting on base more often equates to scoring more runs and ultimately winning more games. But, some methods of reaching base are more effective than others in scoring runs, which is what wOBA measures.

So, what is wOBA in baseball?

Weighted on-base average, or wOBA, measures how often a player reaches base and how they reach base. Hits that produce more runs, like home runs, have the highest weight in calculating wOBA. Hit by pitches and walks have the lowest weight since they are less likely to score runs as a result.

This article explains what wOBA is and how it compares to other stats like OBA and OPS. It also explains what a good and bad wOBA is and covers the all-time wOBA leaders. Lastly, we’ll go into detail on xwOBA and decide if wOBA is a good stat.

wOBA is a stat in baseball used to measure how often a player reaches base and how likely they are to score runs as a result of reaching base.

Here is the MLB’s definition of wOBA:

wOBA is a version of on-base percentage that accounts for how a player reached base — instead of simply considering whether a player reached base. The value for each method of reaching base is determined by how much that event is worth in relation to projected runs scored (example: a double is worth more than a single).

For instance: In 2014, a home run was worth 2.101 times on base, while a walk was worth 0.69 times on base. So a player who went 1-for-4 with a home run and a walk would have a wOBA of .558 — (2.101 + 0.69 / 5 PAs).

As you can see in the formula above, home runs are weighted significantly higher than walks in the wOBA formula. The other ways of getting on base (hit by pitch, singles, doubles, and triples) all weigh between a walk and a home run.

So, wOBA gives more weight to hits that give you multiple bases and are more likely to produce runs. The more bases you get on hits, the higher your wOBA.

On-base average, also called OBA or on-base percentage, is similar to wOBA, but every method of reaching base has the same value in calculating the stat. So a home run, a single, and a walk count the same.

Here is the MLB’s official definition of OBA:

OBP refers to how frequently a batter reaches base per plate appearance. Times on base include hits, walks and hit-by-pitches, but do not include errors, times reached on a fielder’s choice or a dropped third strike. (Separately, sacrifice bunts are removed from the equation entirely, because it is rarely a hitter’s decision to sacrifice himself, but rather a manager’s choice as part of an in-game strategy.)

A hitter’s goal is to avoid making an out, and on-base percentage shows which hitters have accomplished that task the best.

On-base percentage can also be applied as an evaluative tool for pitchers, although this is done less frequently. In such cases, it is referred to as on-base against.

OBA and wOBA both determine how often a player reaches base. But with OBA, it doesn’t matter if you have a walk, a single, or a home run. All methods of getting on base give you the same OBA.

wOBA measures how good a player is offensively. The higher the wOBA, the better a player is at reaching base and producing runs as a result of reaching base.

The more multi-base hits a player has, the higher their wOBA will be. The reason is that multi-base hits (doubles, triples, and home runs) have the highest weight when calculating wOBA.

So, a higher wOBA means a player is getting more home runs, triples, and doubles and likely produces more runs for each hit.

And, an average wOBA doesn’t mean a player is not as good offensively, but that they are hitting more singles or walking more than they are getting multi-base hits.

A low wOBA means the player is either not reaching base as often as they should or getting a lot of walks to get them on base. With many walks, they are still getting on base, but them getting on base is not producing runs. Since walks are weighted lowest in the wOBA formula, more walks mean a lower wOBA.

You may wonder why walks and hit by pitches have a lower weight than singles when all of them only get the batter one base. Well, wOBA also measures how effective each way of reaching base is at scoring runs.

While all three of these only get the batter to first base, other players can still score on each one. For a run to score on a walk or hit by pitch, the bases have to be loaded, and the runner at third will score. But, on a single, up to three runs can score if the bases are loaded since the runners aren’t limited to only one base.

The formula for calculating wOBA is always the same, but some of the numbers within the equation, called factors, change each year.

Here is the MLB’s official formula for wOBA:

Where “factor” indicates the adjusted run expectancy of a batting event in the context of the season as a whole: (unintentional BB factor x unintentional BB + HBP factor x HBP + 1B factor x 1B + 2B factor x 2B + 3B factor x 3B + HR factor x HR)/(AB + unintentional BB + SF + HBP).

The “factor” in the MLB’s formula above changes every year based on the expected number of runs for each event compared to an out. Home runs have the highest factor since they produce the highest number of runs for each home run. Walks have the lowest factor since they have the lowest number of runs as a result of each walk.

First, here’s the general wOBA formula. Each F stands for the factor for the specific scoring method it’s being multiplied by.

wOBA = (F * Non-intentional Walks + F * Hit by Pitch + F * Singles + F * Doubles + F * Triples + F * Home Runs) / (At Bats + Walks + Intentional Walks + Sacrifice Flies + Hit by Pitch)

Now, let’s look at the wOBA formula for the 2021 season, with each specific factor for getting on base. Below are the factors for each method:

Home Runs = 2.007

2021 wOBA = (0.692 * Non-intentional Walks + 0.722 * Hit by Pitch + 0.879 * Singles + 1.242 * Doubles + 1.568 * Triples + 2.007 * Home Runs) / (At Bats + Walks + Intentional Walks + Sacrifice Flies + Hit by Pitch)

The average wOBA in MLB changes every year, but the average wOBA is generally around 0.320. So, a good wOBA is anything above .320, and the higher, the better.

The best offensive players have wOBAs over 0.400. As we detail later in the article, the players with the highest wOBAs in MLB for the 2021 season and career leaders all have wOBAs over 0.400.

A bad wOBA is less than the average of 0.320, and the lower it is, the worse the player is at reaching base and helping their team score runs. The worst wOBAs are 0.300 or lower, and players with wOBAs around these numbers aren’t good offensive players. They are bad at reaching base and producing runs.

wOBA is a good stat because it measures how often a player reaches base and how that player reaches base.

wOBA is important because it gives a different value to each way to reach on base, so certain methods have more weight and, therefore, more impact on a player’s wOBA. Home runs have the highest wOBA value, so the more home runs a player has, the higher their wOBA.

Comparing wOBAs between players and teams is one of the best stats to determine how efficient a team or player is at reaching base for each at bat they have. Higher wOBAs mean players are getting more bases per at bat, leading to more runs.

wOBA and OPS both measure how effective a batter is at reaching base. But, wOBA is better than OPS because it’s a more accurate measurement since it considers how the batter reaches the base.

Career wOBA includes all walks, hit by pitches, hits, and plate appearances throughout a player’s entire career in MLB.

Here are the MLB Career wOBA leaders from Stat Muse:

A player’s season wOBA takes all their hits, walks, hit by pitches, and plate appearances for an entire season.

Here are the 2021 MLB wOBA leaders per Baseball Savant:

Expected weighted on-base average, or xwOBA is the projected wOBA for a player. But it doesn’t always end up being the wOBA that a player ends up with for the season. And, the actual wOBA can be higher or lower than the xwOBA.

The xwOBA is projected based on the exit velocity, the launch angle, and the sprint speed of hit balls by a player. Calculating xwOBA started in 2015 thanks to Statcast.

Here is MLB’s official definition of xwOBA:

Expected Weighted On-base Average (xwOBA) is formulated using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed.

In the same way that each batted ball is assigned an expected batting average, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls since Statcast was implemented Major League wide in 2015. For the majority of batted balls, this is achieved using only exit velocity and launch angle. As of 2019, “topped” or “weakly hit” balls also incorporate a batter’s seasonal Sprint Speed.

Knowing the expected outcomes of each individual batted ball from a particular player over the course of a season — with a player’s real-world data used for factors such as walks, strikeouts and times hit by a pitch — allows for the formation of said player’s xwOBA based on the quality of contact, instead of the actual outcomes. Likewise, this exercise can be done for pitchers to get their expected xwOBA against.

While xwOBA and wOBA may seem like the same stat, they are different because xwOBA doesn’t have any defensive factors.

For example, suppose a player hits a ball that should be a double based on velocity and launch angle, but the center fielder makes an impressive play to catch the ball. wOBA wouldn’t include this in its calculation except for being included as an at-bat. But, xwOBA would include the hit as a double in its calculation since it’s based on the player’s ability to hit and ignores defense.

Here is the MLB’s formula for calculating xwOBA:

All hit types are valued in the same fashion for xwOBA as they are in the formula for standard wOBA: (unintentional BB factor x unintentional BB + HBP factor x HBP + 1B factor x 1B + 2B factor x 2B + 3B factor x 3B + HR factor x HR)/(AB + unintentional BB + SF + HBP), where “factor” indicates the adjusted run expectancy of a batting event in the context of the season as a whole. The factors used in calculating xwOBA are the same ones used in the wOBA formula.

OPS (on-base plus slugging) and wOBA are stats that determine how good a player is at reaching base. As we know, wOBA considers how often a player gets on base, and how they got there.

On the other hand, OPS doesn’t consider how they got on base. OPS is a measurement of on-base percentage and slugging percentage. When calculating OPS, the different types of hits aren’t weighted like they are when calculating wOBA.

OPS does consider extra-base hits since it includes slugging percentage, which calculates how many extra-base hits a batter has. But, it only considers the number of bases per hit, not by any weighted factors for how many runs scored as wOBA does.

Both wOBA and OBA measure how good a player is at reaching base. But, wOBA gives more weight to different hits depending on how many runs are scored on average as a result of each hit.

Batting average (abbreviated as BA or AVG), though traditional and ubiquitous, is perhaps the most flawed of all. On-base percentage (OBP) is more useful, as is slugging percentage (SLG), though the attempt to give us a holistic look by combining those two into one measure, OPS (literally “on-base percentage plus slugging”), doesn’t really work for a number of good mathematical reasons.

We rely on slash lines of AVG, OBP, SLG, despite their one dimensionality, just as we take our temperature to see if we are running a fever, knowing full well that the absence of fever does not necessarily mean we’re healthy.

For evaluating both batters and pitchers, Keith Law, in his excellent book Smart Baseball, recommends weighted on-base average (wOBA), a sabermetric based on linear weights that was introduced in the 2006 book The Book: Playing the Percentages in Baseball by Tom Tango, Mitchel Lichtman and Andrew Dolphin.

wOBA covers all the typical batter’s events (hits, extra base hits, walks, times hit by a pitch, and outs) and applies weights to each of those components that correspond to their impact on the game.

wOBA weights aren’t applied as simplistically as they are with SLG, which wrongly assumes that triples are worth three times more than singles, for example. Instead, weighting for wOBA is systematically determined based on the run scoring environment and updated every year. As baseball changes due to any number of external events, the weighting adjustments used in wOBA make these individual feats more valuable and, naturally, the converse is true. When, for example home runs, are more plentiful, the weighting reduces their value in the wOBA calculation.

Weighting values used in determining wOBA can be different depending on who is doing the calculating. RSNStats relies upon the weights determined by the Fangraphs web site, which makes them available for all years going back to 1871.

In 2020, the formula for wOBA was (0.699×Unintentional BB + 0.728×HBP + 0.883×singles + 1.238×doubles + 1.558×triples + 1.979×HR) / (AB + BB – Intentional BB + SF + HBP).

As with other advanced stats, there are so-called “expected” versions. You’ll recognize these because they start with the letter “x.”

In the case of wOBA, the expected version, xwOBA, can give a clearer view of a batter’s skill because, as former MLB data scientist Sam Sharpe writes, xwOBA focuses on certain “tracked skills to reach a conclusion about what would have happened to balls in play under completely average MLB game conditions.” By eliminating the effects of defense on an offensive effort, expected stats like xwOBA rely on determining a batter’s quality of contact using factors such as exit velocity and launch angle of the batted ball and the batter’s sprint speed to determine the expected outcome as opposed to the actual outcome.

You may be tempted to say you only care about a player’s actual performance and not what typically occurs. But since batters can’t control what happens when the ball leaves the bat, it’s useful to evaluate the player’s contribution based on what typically happens given a certain combination of offensive characteristics.

For example, a batter who reaches safely on a misplayed ball gets lucky. wOBA credits the player with the result. But xwOBA likely concludes that the batter’s performance, as measured by a variety of characteristics, would under average conditions, likely been an out. xwOBA, therefore, may give you a more realistic understanding of the player’s actual skills.

Another useful metric for evaluating pitchers is FIP: Fielding Independent Pitching. This is because once a ball is put into play, there’s not much difference in talent among pitchers. As Tom Tango notes, what you see might tell you there’s a difference but much of that is random variation.

Pitching wins are really immaterial. More reliable measures for evaluating pitchers are their strikeouts, walks, hit-by-pitch and home runs allowed. These are the actions that a pitcher truly controls.

FIP abstracts away the fielding plays to give you a measure, much like Earned Run Average (ERA), of the runs allowed by what the pitcher controls most.

wOBA, or Weighted On-Base Average, is a way to take into account different values for each hit. Batting average gives a home run the same value as a single, whereas wOBA weighs a home run higher than a single, etc. It ends up being a much better way of assessing a hitter.

The league average wOBA is around .315. Anything above .365 is great, while anything below .295 isn’t close to great. When you pick your batter, judging his ability from wOBA over batting average is a more efficient method.

One way to find value using wOBA is to look at the difference between wOBA and batting average. If a player has a low batting average or on base percentage, but a good wOBA, his at bats are more efficient than those two stats are showing.

Checking splits on any statistic is a step you should take in evaluation. As a basic rule, right handed hitters see the ball better against left handed pitchers and end up putting up better statistics against them and vice versa. For some batters it is more pronounced than others and in some rare cases a batter bucks the trend and hits better or at least equally against pitchers of the same “handedness.”

Extreme cases may push that hitter to see fewer at bats when a different handed relief pitcher comes in, but as long as the matchup is strong against the starter, you are still maximizing your matchup.

Pitchers also have a wOBA statistic, but it is based on what hitters accomplish against them. Again, basing performance on wOBA is better catch all statistic than batting average or its ilk. Looking at wOBA against will help sort through that slate’s most effective pitchers.

We can’t be assured that a pitcher will face a certain number of lefties or righties in any matchup, but we can see how many lefties vs. righties each team sends out in their average lineup. Some teams are going to be stronger against one side of the plate than the other and if your pitcher matches up well against a lineup based on splits, you are in business.

In baseball, wOBA (/'woʊbə/, or weighted on-base average)[1] is a statistic, based on linear weights,[2] designed to measure a player's overall offensive contributions per plate appearance. It is formed from taking the observed run values of various offensive events, dividing by a player's plate appearances, and scaling the result to be on the same scale as on-base percentage. Unlike statistics like OPS, wOBA attempts to assign the proper value for each type of hitting event. It was created by Tom Tango and his coauthors for The Book: Playing the Percentages in Baseball.[3]

In 2008, sabermetrics website FanGraphs began listing the current and historical wOBA for all players in Major League Baseball.[4] It forms the basis of the offensive component of their wins above replacement (WAR) metric. Sites such as The Hardball Times have studied wOBA and found it to perform comparably to or better than other similar tools (OPS, RC, etc.) used in sabermetrics to estimate runs.[5][6] The Book uses wOBA in numerous studies to test the validity of many aspects of baseball conventional wisdom.

The benefit of wOBA compared to other offensive value statistics is that it values not just whether the runner reached base but how.[7][8] Events like home runs, walks, singles, etc. are given their own weight (or coefficient) within the linear formula. The weighting is based on the increase in expected runs for the event type as compared to an out. The coefficients change each season[9] based upon how often each event occurs.

Because the coefficients are derived from expected run value, we can use wOBA to estimate a few more things about a player's production and baseball as a whole. When using the formula (shown below), the numerator side on its own will give us an estimate of how many runs a player is worth to his team. Similarly, a team's wOBA is a good estimator of team runs scored, and deviations from predicted runs scored indicate a combination of situational hitting and base running.[10]

Per Fangraphs, the formula for wOBA in the 2019 season was:[9]

w O B A = ( 0.69 ∗ N I B B ) + ( 0.719 ∗ H B P ) + ( 0.87 ∗ 1 B ) + ( 1.217 ∗ 2 B ) + ( 1.529 ∗ 3 B ) + ( 1.94 ∗ H R ) A B + B B − I B B + S F + H B P {\displaystyle wOBA={\frac {(0.69*NIBB)+(0.719*HBP)+(0.87*{\mathit {1}}B)+(1.217*{\mathit {2}}B)+(1.529*{\mathit {3}}B)+(1.94*HR)}{AB+BB-IBB+SF+HBP}}}

where:

—————

The formula for the 2018 season was:[9]

w O B A = ( 0.69 ∗ N I B B ) + ( 0.72 ∗ H B P ) + ( 0.88 ∗ 1 B ) + ( 1.247 ∗ 2 B ) + ( 1.578 ∗ 3 B ) + ( 2.031 ∗ H R ) A B + B B − I B B + S F + H B P {\displaystyle wOBA={\frac {(0.69*NIBB)+(0.72*HBP)+(0.88*{\mathit {1}}B)+(1.247*{\mathit {2}}B)+(1.578*{\mathit {3}}B)+(2.031*HR)}{AB+BB-IBB+SF+HBP}}}

—————

The following table serves as an aggregate summary of various wOBA scales available online.[10][11]

The formula below appeared in The Book.[12]

w O B A = ( 0.72 ∗ N I B B ) + ( 0.75 ∗ H B P ) + ( 0.90 ∗ 1 B ) + ( 0.92 ∗ R B O E ) + ( 1.24 ∗ 2 B ) + ( 1.56 ∗ 3 B ) + ( 1.95 ∗ H R ) P A {\displaystyle wOBA={\frac {(0.72*NIBB)+(0.75*HBP)+(0.90*{\mathit {1}}B)+(0.92*RBOE)+(1.24*{\mathit {2}}B)+(1.56*{\mathit {3}}B)+(1.95*HR)}{PA}}}

where: