ABS didn’t replace the umpire — it added a review. The human still calls every pitch; the batter, catcher, or pitcher can tap the helmet and let Hawk-Eye settle it. Two challenges a team: keep it on a win, lose it on a miss.
Across 1,295 games and 381,733 pitches (2026-03-25 to 2026-07-01), players challenged 5,356 times and 53% were overturned — a near coin flip with the game on the line. The rest is turning that coin flip into a decision.
1 · The bottom-edge problem
Umpires miss 6.4% of called pitches against the ABS zone. The misses aren’t random — they cluster on the edges, worst on the bottom. A low strike at the knees is the hardest call in baseball, and it is where challenges concentrate.
2 · It comes down to distance from the edge
The controlling variable is distance from the zone edge. Two inches off the plate, a missed call is a near-certain overturn; at the edge, the overturn rate collapses toward a coin flip. Every downstream decision — who challenges, and when — negotiates that curve.
3 · The catcher’s eye is real, and measurable
Catchers are the best challengers — 59% overturned, against 47% for batters and 35% for pitchers — and they initiate 51% of all challenges. Aggregate rates hide the skill, so we fit each catcher a perception sharpness (a sigma, in inches): how close to the edge they can still separate a ball from a strike. The sharpest aren’t luckier; they read the margin better.
4 · Winning teams decide differently
Net challenge value — runs gained on overturns minus the cost of wasted challenges — spans 1.9 wins between the best team (CIN) and the worst (PIT). The gap is rarely eyesight; it is allocation: burn an early challenge on a low-stakes call and you have nothing left when a game-deciding pitch is missed in the eighth.
5 · The cost of a challenge is not a flat number
The common shortcut prices a lost challenge at a flat ~0.2 runs. It isn’t flat. Losing your first challenge in the first inning forfeits eight innings of optionality — closer to 0.5 runs; losing your second is cheap. So the confidence needed to justify a challenge should fall through the game, from roughly 47% in the first inning to ~21% in the ninth. Conserve early, spend late.
6 · The leverage twist
Stakes bend it further. Same pitch — bases loaded, 3-2, two out, tied. In the top of the first, break-even is about 12%: the game is long, hold your shot. In the bottom of the ninth, it is under 1%: challenge almost anything. And a sharper-eyed catcher carries a higher bar — their challenges are worth more, so a wasted one costs more.
The prize
Add up every unchallenged umpire miss that had positive expected value, league-wide, and it comes to about 1,139 runs — near 114 wins — left on the field. Not from sharper eyes; from better detection and timing.
Every claim here is checkable in the explorers, and the model is laid out in the methodology.