Weighted On-Base Average — a hitter rate stat that weights each offensive event by its actual run value.
Traditional batting average treats every hit the same; a bloop single and a 450-foot home run both nudge the average up by one part in the denominator. On-base percentage is better — at least walks count — but it still treats a walk and a home run identically. Slugging percentage swings the other way, weighting power but ignoring walks entirely. None of those numbers reflects how much each event actually contributes to scoring runs.
Weighted On-Base Average — wOBA — solves that. Tom Tango's research mapped every offensive outcome to a run value using historical play-by-play data. A walk is worth roughly 0.69 runs above an out in a typical environment; a single is worth about 0.88; a double 1.24; a triple 1.56; a home run 2.10. wOBA averages those run values across a hitter's plate appearances and then scales the result so the league average equals league on-base percentage. That last step is cosmetic: it lets you look at a wOBA and instantly know whether it's good without memorizing a new scale.
Because the coefficients are tied to run values, wOBA is one of the most run-correlated hitter stats available. Two hitters with identical wOBAs are, in expectation, producing the same run value per plate appearance even if one is a high-walk slap hitter and the other a low-OBP slugger. The flip side is that wOBA still includes batted-ball luck — a hitter running unsustainably high BABIP will post a wOBA that overstates his true talent.
xwOBA, the Statcast cousin, replaces the actual hit/out outcome on contact with a league-average expectation based on exit velocity and launch angle. The gap between wOBA and xwOBA is one of the most reliable hitter regression flags in the public data.
Our hitter projections start from a rolling wOBA blended toward Steamer-style aging curves. For totals, we sum lineup wOBA-against-handedness and convert to expected runs; for player props, we lean on xwOBA splits.