For 4 years now, I’ve been updating you on the altering contours of the strike zone. By my depend, that is the tenth installment in that sequence and the sixth particularly in regards to the accuracy of ball-strike calls on the perimeters of the zone. With the implementation of the ABS problem system in 2026, these updates will little doubt begin to look a bit totally different. That is our final umpire accuracy replace of the pre-ABS period, so let’s take inventory of the place we’re on the finish.
After a tiny dip in 2024, umpires had been again on observe in 2025, posting a record-high accuracy price of 92.83% general. In truth, 2024 was the one 12 months within the pitch-tracking period wherein umpires didn’t set a report for accuracy. Nonetheless, this newest report got here with a little bit of controversy. Early within the season, pitchers and catchers picked up on the truth that the strike zone appeared to have shrunk. The league tightened up the requirements that it used to grade umpires, lowering the dimensions of the buffer zone across the edges of the zone. In consequence, accuracy shot up particularly on pitches outdoors the zone, much more particularly, on pitches simply above the highest of the zone, inflicting pitchers and catchers to complain that they had been shedding the excessive strike.
This graph reminds us of a pair details that may simply be so apparent that we hardly ever take into consideration them. First, the overwhelming majority of takes come on pitches outdoors the strike zone. After all they do; these are the pitches you’re not alleged to swing at. This 12 months, for instance, 68% of the calls umpires needed to make got here on pitches outdoors the strike zone. Second, it’s simpler to establish balls than it’s to establish strikes. After all it’s; the world outdoors the zone is lots larger than the world contained in the zone.
These details lead us in two barely contradictory instructions. First, a lot of the catching up that umpires have executed over the previous couple of a long time has needed to come on pitches contained in the zone, which meant calling extra strikes. They began out with far more room for enchancment there. From 2008 to 2025, they added 13 proportion factors to their accuracy contained in the zone and 7 factors outdoors the zone. Second, as a result of most takes come on balls, the most secure approach to enhance your accuracy general is to enhance at calling pitches outdoors the zone, which implies calling extra balls. Proper round 2021, umpires appeared to search out their stage. As an alternative of plateauing, they stored bettering by calling extra balls each inside and outdoors the strike zone. As general accuracy stored bettering, accuracy contained in the zone fell in every of the previous 4 seasons. It took its largest dip by far in 2025, falling by 1.7 proportion factors. That dynamic is much more obvious once you look solely at pitches within the shadow zone, the world one baseball’s width from the sting of the zone on both facet.
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Again when this controversy reared its head in Might, I ran an identical graph, however the departure in 2025 on this graph is barely extra excessive, as a result of that development towards calling extra balls elevated because the season went on. Originally of the pitch monitoring period, the perimeters of the zone had been far more permeable in each instructions, however umpires had been a lot better at figuring out balls than strikes. They closed that hole by 2017 and stored on going, operating higher charges on pitches that simply clipped the zone than those that simply missed it. However that solely lasted for a number of years. In 2023 and 2024, they ran practically an identical accuracy charges on these borderline pitches. It was honest to imagine that perhaps we’d reached the restrict of how good the human eye could be at figuring out whether or not or not pitches clipped the perimeters of an invisible rectangle. That assumption remains to be in play due to the way in which the advance went down in 2025. Even on these nearer takes within the shadow zone, there’s nonetheless extra space outdoors the zone than inside it, and 55% of the calls umpires should make are on pitches outdoors the zone. Calling a extra correct zone general meant calling extra balls and lacking extra strikes.
Clearly, that development can’t proceed endlessly. That yellow line solely ticked up ever so barely in 2025; if umpires had been to err any additional in favor of calling balls, it could begin heading again down. If we weren’t heading towards a problem system, I’d be actually to see what would occur subsequent. Would tightening up the zone proceed to end in extra balls and fewer strikes, even to the purpose the place umpires grew to become much less correct? Or would this new grading system ultimately enhance accuracy on each as umpires continued to get used to it?
We should still get the solutions to those questions, as a result of the ABS problem system received’t be practically as disruptive as you may assume. Baseball Savant’s minor league search operate tells us that in 2025, even with the problem system, minor league umpires had been extra correct than their main league counterparts by simply 0.3 proportion factors, main 93.1% to 92.8%. However these numbers don’t say precisely what you suppose they are saying.
In keeping with a superb explainer from JJ Cooper of Baseball America, Triple-A noticed roughly 4 challenges per recreation in 2025, and 50% of them had been profitable. It’s affordable to imagine that main leaguers might be no less than somewhat bit higher at selecting their spots for challenges. In keeping with Anthony Castrovince of MLB.com, throughout the spring coaching check drive of the system, 52.2% of challenges overturned the decision in query. Let’s assume these charges will maintain and apply them to the 2025 numbers. That might minimize out 5,074 missed calls, elevating the general accuracy from 92.8% to 94.2%. On a per-game foundation, that may drop the variety of misses from 10.9 to eight.8. The problem system will overturn 2.1 missed calls per recreation, however that’s provided that the numbers maintain. They won’t.
Exterior the shadow zone, minor league umpires had been proper 99.71% of the time. This quantity was undoubtedly boosted by the problem system. They missed simply 838 occasions all season lengthy, and as most of these misses got here after the fifth inning, I’d additional assume that always sufficient, these misses got here after the wronged staff had already exhausted their challenges. Within the majors, even and not using a problem system, umpires obtained 99.73% of calls outdoors the shadow zone proper, barely higher than their minor league counterparts. In 2025, they missed simply as soon as each 4 video games, however as a result of these calls are probably the most egregious, they’re those we bear in mind most clearly. The problem system will probably deliver that quantity even decrease, however they’re ranging from a really excessive place.
The hole is greater contained in the shadow zone, the place main league umpires led minor league umpires in accuracy, 82.2% to 81.6%. At this level chances are you’ll be questioning how minor league umpires may have been extra correct general in the event that they had been worse each inside and outdoors the shadow zone. The explanation the numbers work out is that, as you’d count on, minor league pitchers have worse management, which leads them to hit the perimeters of the zone much less steadily. Main league pitchers hit the shadow zone 39.5% of the time, whereas minor leaguers hit it 36.4% of the time. So minor league umpires had been capable of pump up their general accuracy price by seeing extra of the better, non-shadow zone calls. This additionally implies that within the minors, a better proportion of challenges had been wasted on calls that weren’t notably shut. The challenges within the majors could effectively come on nearer pitches, which may imply a downtick within the overturn price. That quantity I quoted earlier, 2.1 overturned calls a recreation, may effectively be too excessive. In case you ever noticed an outrageous missed name and remarked that it could’ve been referred to as accurately in a Triple-A recreation, don’t be so positive. This 12 months, main league umpires had been extra correct even with out the assistance of ABS. They’re already fairly good.