Methodology

How We Score MLB Challenges

Every number on Abstap traces back to one public dataset and a handful of transparent formulas. Here is exactly how the data is sourced, how the Robbery Score is calculated, and where the method has limits.

4,678
challenges scored
2,484
overturned
53%
success rate

What Abstap measures

Abstap tracks every Automated Ball-Strike (ABS) challenge in Major League Baseball: a batter, catcher, or pitcher asks the system to review a ball-strike call, and ABS either overturns the umpire or confirms the call. We record each challenge with its full game context — inning, count, score, baserunners, the pitch location, and the umpire behind the plate — then rank them.

If you're new to the system itself, start with our plain-English guide to ABS challenges. This page is about the numbers.

The Robbery Score

Not every overturned call matters equally. A phantom strike three to end a tie game in the ninth is a bigger deal than a missed call in a blowout. The Robbery Score is how we rank them. It is the product of two independent measures:

Robbery Score = Leverage Index × Call Magnitude
how much the moment mattered × how badly the call missed

Call Magnitude — how badly the call missed

Call magnitude is how far off the call was, in inches, against the 17-inch rulebook zone — sized per batter from the pitch's reported top and bottom. ABS counts a pitch as a strike if any part of the ball touches the zone, so for a pitch called a strike but really a ball we measure the gap to the ball's nearest edge (accounting for its ~2.9-inch diameter) — which is why those numbers track what a broadcast strike-zone graphic shows, not a larger center-of-ball figure.

  • A strike overturned to a ball: the ball was outside the zone. Magnitude is the gap from its nearest edge to the zone — how far it was from being a strike.
  • A ball overturned to a strike: the ball was inside the zone. Magnitude is how far inside the edge the pitch was — how clearly it should have been a strike.

Either way, a larger number means a more obvious miss. Pitches with no reported location can't be measured and are left unranked.

Leverage Index — how much the moment mattered

Leverage Index (LI) is a standard sabermetric idea: how much a single play can swing a game's outcome. An average situation is about 1.0; a blowout collapses toward 0; a tie game with the bases loaded in the ninth climbs to 5 or higher. We compute LI from the inning, half-inning, outs, baserunners, and score differential at the moment of the pitch.

Our LI is a parametric approximation anchored to well-known game states, not the original (unpublished) Tango leverage table. It is built for ranking — sorting the day's challenges by how much was at stake — and it does that reliably. It is not intended as a precise win-probability figure.

What counts

  • Regular-season ABS pitch challenges are the default everywhere a leaderboard ranks calls. Spring training is shown separately and labeled — spring uses looser rules and far more games, so the two should never be mixed.
  • Overturned vs. confirmed. A challenge is "overturned" when ABS reverses the umpire and "confirmed" when it agrees. Success rate is overturned ÷ total challenges.
  • The robbery leaderboards rank by Robbery Score — overturned calls only, sorted by leverage × magnitude.

Data source & update cadence

All data comes from the public MLB Stats API — the same feed that powers official box scores. We sync the previous day's games every morning at roughly 6 AM ET, so leaderboards reflect completed games. Pitch locations, umpire assignments, and challenge outcomes all come from that feed; we do not hand-enter or estimate calls.

Limitations & honest caveats

  • Leverage Index is an approximation. Use it to compare the relative stakes of two challenges, not as an exact win-probability swing.
  • Baserunner state is coarse. The MLB feed reports baserunners as a category (empty, men on, scoring position, loaded) rather than exact bases, so LI uses the most common configuration for each. It barely affects ranking but isn't exact.
  • Counts are ABS-only. Every total and leaderboard here counts only ABS pitch challenges (the MLB feed's MJ review type), matching how the official ABS leaderboard is defined. A small tail of non-ABS reviews (manager, fair/foul) exists in the feed but is excluded from these numbers.

Using & citing this data

Journalists, broadcasters, and researchers are welcome to cite Abstap. Please attribute figures to Abstap (abstap.com) and link to the relevant page. For citation guidance, story angles, and data requests, see the press & data page.