"How hard can it be to call a ball or a strike?"
For 150 years, one human being stood 60 feet, 6 inches from a 95-mph fastball and decided the fate of at-bats. In 2026, teams got the power to appeal that decision to a machine. The data reveals how badly they needed it — and how hard the job really is.
DSC 106 · University of California San Diego · Spring 2026
The rulebook says a strike is any pitch that passes through the zone — a rectangle extending from the batter's knees to the midpoint of their torso, and from the inner to outer edges of home plate. Simple enough. But the zone that actually gets called is a different shape entirely.
Below is where umpires have called every pitch in the 2026 MLB season. Toggle to see the landscape from the catcher's perspective — the yellow box is the true ABS zone. The heat outside it is what's being missed. Toggle between called strikes and the error rate, and between left- and right-handed batters, to see how the zone shifts.
Darker cells = more pitches called there. Yellow rectangle = ABS strike zone boundary. Hover a cell for exact counts.
The pattern is impossible to miss. Umpires squeeze the top of the zone and give away the bottom. They shade toward the catcher's glove, widen for certain counts, and shrink the zone for elite pitchers. These aren't random errors — they're systematic, predictable biases that batters and catchers could now, for the first time, appeal directly.
Across 69,000 pitches in the 2026 season, umpires disagreed with the ABS geometric zone on roughly 9.5% of called pitches — not a lot, but in a game decided by fractions of a run, every one of those calls matters.
Here's where the and-but-therefore of ABS gets interesting. The system gives every team the same resource: two challenges per game. Succeed, and you keep the challenge. Fail, and it's gone. By the end of May, the gap between the best and worst challenge teams had become striking.
The bar below shows each team's batter challenge overturn rate — the percentage of challenges where ABS agreed with the batter, not the umpire. Hover a bar for the full breakdown. Use the sort buttons to reorder.
Dashed line = MLB average. Only teams with ≥ 20 challenges shown. Hover a bar for details.
Texas leads the league at over 63% — meaning nearly two out of every three challenges they make are overturned in their favor. Milwaukee sits last, winning fewer than one in three. That gap represents a genuine strategic skill that is being learned and exploited in real time across the league.
Challenging well isn't just about identifying bad calls — it's about reading pitch location in the fraction of a second after the ball crosses the plate, estimating how close to the edge the pitch was, and deciding whether the probability of a successful challenge outweighs the cost of losing one. It is, in other words, a statistical decision made instinctively.
The scatter below shows every qualified MLB batter by how often they challenge and how often they win. The color axis shows net value added versus expectation — green players are consistently making smart decisions, red players are wasting challenges on long-shot pitches. Filter by team or hover any dot for the full picture.
Color = net challenge value added vs. expected (green = above, red = below). Dashed lines = MLB averages. Hover a dot for player details.
The upper-left quadrant — high success rate, low frequency — is where the most disciplined challengers live. They pick their spots. The lower-right quadrant is where challenges go to die: high frequency, low win rate. Davis Schneider of Toronto stands alone as the most valuable challenger in baseball through May, winning 9 of 12 challenges for a net value of nearly +5 challenge equivalents above expectation.
An overturned strike becomes a ball. An overturned ball becomes a strike. Those aren't abstract statistics — they change counts, extend at-bats, and, in the most consequential cases, flip strikeouts into walks and walks into strikeouts. Below is the scoreboard of how many at-bat outcomes have been directly altered by ABS challenges for each team so far this season.
Green bars = strikeouts avoided (ball called → strike overturned → batter survives). Red bars = strikeouts gained against (against that team's pitchers). Hover for details.
Detroit leads the league in net outcome advantage. Atlanta and Colorado have given back nearly as many outs as they've avoided — their pitchers are getting punished by opponents who challenge smartly, while their own batters aren't challenging well enough to compensate. At the team level, ABS is already acting as a second front in the competitive arms race.
Umpires miss calls. But they're also professional athletes making a judgment at the pace of a fastball. Before you judge too harshly — try it yourself. Below are ten real pitches from the 2026 MLB season. Watch the ball travel from the pitcher's hand to the plate. When it crosses, you have two seconds to call it. Ball or strike — same as a real umpire.
At the end, we'll show you how your accuracy stacks up against the actual MLB umpires who called these pitches.
Watch 10 real 2026 MLB pitches. Call ball or strike before the timer runs out. Can you beat a professional umpire?
The single most important insight from the first months of ABS is one that no one fully anticipated: the difficulty of calling balls and strikes isn't a flaw in human performance — it's a property of the problem itself. A pitch on the corner moves 6 inches in the last 10 feet of flight. Perspective distortion from behind the plate makes the inside corner look different from the outside corner. And the zone itself is a moving target, shifting inch by inch with every batter's stance.
Even with the machine available for appeals, teams are only converting roughly half their challenges. Even experienced catchers, who have spent entire careers reading pitch location, are getting it wrong nearly as often as right on the hardest pitches. The human umpire was not failing at an easy task. They were succeeding at an incredibly hard one.
ABS didn't expose umpires as incompetent. It exposed the strike zone as the most contested two-square-foot rectangle in professional sports — and gave every batter, pitcher, and fan a front-row seat to just how close every call really is.
Data: Baseball Savant ABS Leaderboard & Statcast Pitch Data — 2026 MLB Regular Season through May 18, 2026