xwOBA / xwOBA

Batter

Expected wOBA: the mean of Savant's per-pitch estimate over wOBA-denominator plate appearances that carry an estimate. See runbook section 10.

Agreement with Savant

Checked nightly. Agreement tolerance: ±0.001.

Pitcher

Expected wOBA against: the mean of Savant's per-pitch estimate over wOBA-denominator batters faced that carry an estimate. See runbook section 10.

Agreement with Savant

Checked nightly. Agreement tolerance: ±0.001.

Shown for: batter and pitcher.

Formula

sum(xwoba_num) / NULLIF(sum(xwoba_den), 0) — the mean of Savant's per-pitch estimate over wOBA-denominator plate appearances that carry one.

Inputs

pitches.estimated_woba_using_speedangle
plate_appearances.xwoba_num
plate_appearances.xwoba_den

Era caveats

Untracked contact leaves the denominator

Savant excludes batted balls it could not track rather than imputing them, and matching that is what closed the residual. The exclusion reaches the three expected stats by two different routes: xBA and xSLG subtract at aggregation time — at-bats minus at-bats whose batted ball carries no estimate — while xwOBA never counts them at all, because a plate appearance with no estimate never enters xwoba_den when its fact row is built. (runbook §10)

Three tracking systems across the seasons shown

Rows carry a tracking_era of trackman, hawkeye or hawkeye_bat (migration 001). The systems differ in what they measure and how precisely, so long spans cross a measurement boundary as well as a rule one.

Version history

2026-08-09 — Agreement tolerance tightened from ±0.005 to ±0.001 once the residual was removed rather than recorded. (runbook §10)