What is Chase Rate? Definition, Formula, and Example
Chase rate is the percentage of pitches outside the strike zone that a batter swings at, measuring plate discipline where a lower number indicates a more selective hitter.
Plain-English Definition of Chase Rate
Chase rate is the share of pitches outside the strike zone that a hitter swings at. A low chase rate means the hitter lays off junk; a high chase rate means he expands the zone. It is the cleanest single-number answer to "how disciplined is this bat?" — pitch recognition shows up here before it shows up in walk rate, because walks are a downstream consequence of not chasing. On the pitcher's side, generating chase is the fastest way to post low walk totals and high strikeout totals without overpowering anyone.
How Chase Rate Is Calculated
Chase Rate = Swings on pitches outside the zone / Total pitches outside the zone
Statcast and pitch-tracking systems define the strike zone per-player: from the midpoint between the shoulders and belt down to the hollow of the kneecap, inside-edge to outside-edge of the plate, adjusted for each hitter's stance. Any pitch whose center crosses outside that box is "out of zone." Swings on those pitches — contact, whiff, or foul — count as chases.
League-average chase rate sits near 28-30% in modern MLB. Grading:
- Under 20% — elite discipline
- 22-25% — above average
- 28-30% — league average
- 33%+ — below average
- 40%+ — extreme free swinger
Worked Example: Soto vs. Perez
Juan Soto posted an 18.3% chase rate in 2024 — the lowest among qualified hitters and roughly 12 percentage points below league average. That discipline fed an 18.1% walk rate and a .419 OBP. On the opposite end, Salvador Perez ran a 40.4% chase rate the same season; he walked just 4.7% of the time despite hitting 27 home runs. Same league, same year — two completely different approaches to the strike zone.
On the pitcher's side, Paul Skenes induced chase swings on 33.9% of his out-of-zone offerings in 2024, well above the pitcher average near 28%, which is a major reason he finished with a 1.96 ERA and struck out 11.5 per nine.
Why Chase Rate Matters
Chase rate is among the stickiest year-over-year stats a hitter has — it stabilizes by about 50 plate appearances, which is why it is a far better early-season signal than batting average. Front offices use it to project walk rate, BABIP, and xwOBA going forward. In DFS, a hitter with a sub-20% chase rate facing a wild pitcher gets a walk-rate boost that rarely shows up in traditional projection models. For pitchers, chase rate is the mechanism by which Stuff+ turns into strikeouts — nasty stuff that hitters refuse to chase produces fewer Ks than the raw pitch quality would suggest.
Limitations and Misconceptions
Chase rate is not quite the same as FanGraphs' O-Swing%, though the two are highly correlated — O-Swing% uses slightly different zone definitions. Chase rate also does not penalize a hitter for taking close strikes; for that, look at swing-decision models like SEAGER. A low chase rate is not automatically good — Joey Gallo had elite chase numbers alongside historic strikeout totals, because laying off out-of-zone pitches does not help if you also miss the ones in the zone. Read chase rate alongside whiff rate to get the full discipline picture.
Related Terms
In Legends Deck
Chase rate drives the Plate Discipline rating on every Legends Deck hitter card and the Chase Generation rating on pitcher cards. In the sim, a hitter with a sub-20% chase rating forces the pitcher deeper into counts, creating more walks and more hitter's-counts against the cards stacked opposite him — meaning a Soto-grade discipline rating actually changes how at-bats unfold, not just the slash line at the end.