What is wOBA?
wOBA is an offensive stat that seeks to fix some of the flaws in OPS. OPS is a good measure of offense but it has some flaws such as treating a point of on base percentage as equal to a point of slugging, and saying a double is twice as valuable as a single. wOBA looks to correct these flaws and display them in a league neutral context.
What is a good wOBA?
wOBA is scaled with on base percentage. .330 is average, .300 is below average, .360 is above average and .400 is elite.
What numbers factor into wOBA?
There are seven numbers that affect wOBA: singles, doubles, triples, home runs, reaching via error, walks, and hit by pitches. Each of these numbers is multiplied by a coefficient for each league based on the overall league numbers then adjusted to make .330 average.
Where do these coefficients come from?
The wOBA coefficients are calculated with this spreadsheet by JT Jordan. They are based off the total offensive production of the league.
If it’s based on the league numbers do coefficients change everyday?
No. Until the season is over we use wOBA coefficients from the previous season. This means there will be some adjustments during the post season.
Why are these numbers slightly different than wOBA elsewhere?
Several reasons
- Some versions of wOBA scale average to the league average on base percentage, instead of a flat .330 like we do.
- Some versions of wOBA include stolen base numbers
- Some versions of wOBA do not include pitcher numbers. Ours does, and this is a flaw we’ll look to fix in the future.
Is wOBA league adjusted?
Yes. No matter what the run environment is .330 is always average.
Is wOBA park adjusted?
No. In the future we’ll add park adjusted wOBA.
Why doesn’t wOBA show up in players career numbers or across leagues?
The way our stats are calculated currently doesn’t support combining wOBA coefficients from multiple years or leagues. We’re working to fix this.
