William Purnell-Imagn Pictures
I’ve been writing concerning the strike zone for a number of years now, and if there’s been one overarching theme to my work to this point, it’s the inescapable takeaway that umpires are glorious at what they do. When Main League Baseball launched PITCHf/x in 2008, umpires acquired 84.1% of ball-strike calls proper in response to the Statcast strike zone. Over the intervening years, whereas ever-nastier stuff and a revolution in pitch framing had made their jobs more durable and more durable, umpires did nothing however get higher. Accuracy broke 92% in 2021 and inched its means towards 93% over the subsequent two seasons. That development of enhancing yearly lastly modified in 2024.
As I wrote yesterday, final season marked the primary time that umpires acquired worse reasonably than higher. That’s fascinating sufficient by itself, however proper when it was time to wonder if they’d gotten nearly as good as they may get, the foundations of the sport modified. Over the offseason, a brand new labor settlement included a change to the way in which that umpires are assessed by the league. The grading acquired a lot tighter, lowering the buffer across the edges of the strike zone from two inches to three-quarters of an inch. The strike zone is similar, however umpires are being judged far more tightly. Let’s dive into the numbers and see what appears to be like completely different to this point this season. Right here’s a graph that reveals general accuracy in each season of the pitch monitoring period.
The yellow line reveals general accuracy, and it’s ticked again up from 2024. Though it’s early within the season, a time when umpires are at their least correct, they’re nonetheless doing higher than they did final yr. Accuracy fell from 92.81% in 2023 to 92.53% in 2024, and is now again as much as 92.63%. In actual fact, in case you look solely at March and April stats – which is extra truthful, as a result of umpires are worse earlier within the season – you’ll discover that umpires simply had their greatest opening month of the season ever. They referred to as 82% of pitches within the shadow zone appropriately.
The truth that accuracy has ticked again up isn’t essentially what pursuits me. I think that was prone to occur anyway. Umpires have been getting higher each season for many years, and one very barely worse season didn’t imply they have been completed enhancing solely. What pursuits me is the way in which the pink and blue traces within the graph above diverged so drastically. The graph under reveals the impact extra clearly, as a result of it reveals solely pitches within the shadow zone, inside one baseball’s width of the sting of the zone, the place an umpire’s judgment is admittedly examined.
All the way in which on the proper of that graph, the paths of these pink and blue traces is the actual story right here. Sure, umpires have been barely extra correct this season, however there’s a really clear sample to their enchancment. They’ve been a lot better at judging pitches outdoors the strike zone and far worse at judging pitches contained in the strike zone. In different phrases, they’ve been calling much more balls. That’ll make you extra correct as a result of, naturally, gamers are inclined to swing at extra pitches within the zone and take extra pitches outdoors it. The blue line reveals that efficiency on pitches contained in the zone fell to its lowest degree since 2016. That’s 10 years of progress erased! This season, 42.7% of ball-strike calls within the shadow zone have ended up as strikes. That’s the bottom fee ever recorded. Right here’s what that appears like in a line graph.
Take a look at the way in which that line has shot down this season. Now contemplate the truth that to this point, 44.9% of these pitches truly hit the strike zone, the very best fee in 10 years. Right here’s the identical graph, however with zone fee additionally included.
The zone fee actually doesn’t appear to have any bearing on the referred to as strike fee, particularly this yr. Because of this pitchers and catchers have been telling The Athletic that the strike zone is shrinking. Sure, accuracy has improved, but it surely’s improved very a lot within the batter’s favor. Not solely that, however the Giants have been much more particular with their complaints, telling the San Francisco Chronicle that the excessive strike particularly has been disappearing. As a way to study that, I pulled accuracy knowledge on three specific components of the shadow zone. Let’s begin on the perimeters of the plate. Assault zones 14 and 16 cowl the shadow zones on all sides of the plate — 14 is inside to a right-handed hitter, 16 is outdoors — however exclude pitches within the prime and backside shadow zones. We’ll get to the corners later. The development right here has been clear for a very long time.
Umpires have been steadily getting higher on the perimeters of the plate, and that enchancment has typically come on pitches outdoors the strike zone. They’ve been getting higher at figuring out balls, however this season, for the primary time, that enchancment has actually come on the expense of their accuracy contained in the zone. They’re nonetheless extra correct general, however they’re lacking extra strikes than they used to. Right here’s one other means of viewing these traits. The graph under reveals the common horizontal location of each ball or referred to as strike in these two zones. The grey space reveals the precise width of house plate.
As you possibly can see, the referred to as strikes have been getting nearer and nearer to the precise fringe of the plate, whereas the referred to as balls have been getting farther and farther away. The typical referred to as strike on the sting of the plate actually is correct on the sting of the plate. Nevertheless, this season, all 4 traces have ticked a bit nearer to the plate. The zone is simply plain tighter.
Now let’s take a look at the underside of the strike zone. As I’ve written earlier than, through the years, umpires have gotten extra correct on the backside of the zone by calling extra strikes. The graph under reveals assault zone 18, the underside of the zone over the center of the plate. We’re ignoring the corners once more as a result of we wish to get a way of the place the true backside of the zone is with out letting the perimeters of the plate have an effect on it.
Through the years, the underside of the strike zone has gotten considerably decrease, and catchers across the league have adopted one-knee down stances as a way to earn extra referred to as strikes down there. From 2009 to 2020, the peak of the common referred to as strike on the backside of the zone dropped by 1.92 inches. Nevertheless, ever since, that common has been ticking again up. This season, it’s 0.6 inches greater than it was in 2020. Nonetheless, to this point this season, the impact hasn’t been as drastic as it’s on the sides of the plate, the place umpires have truly gotten worse at figuring out strikes.
Lastly, let’s check out the highest of the zone, the issue space highlighted by the Giants. The graph under reveals assault zone 12, the highest of the zone over the center of the plate, and it definitely appears to be like like San Francisco has some extent. Not solely have umpires been calling a tighter zone up there, however they’ve been calling it so tightly that they’ve truly gotten much less correct general.
This graph doesn’t seem like the others, and there’s a motive for that. The others had straight traces that informed a tidy story. On the perimeters, umpires have been at all times good at figuring out strikes, and through the years they’ve gotten higher at figuring out balls, primarily squeezing the zone as they acquired higher at discovering the sides of the plate. On the backside of the zone, umpires have been at all times good at figuring out balls, however they step by step improved at figuring out strikes, reducing the zone.
The highest of the strike zone is rather a lot fuzzier than the perimeters and the underside. Umpires can’t simply look down at house plate to information them visually, and the highest of the zone varies far more from batter to batter than the underside. Furthermore, the highest of the rulebook zone varies essentially the most from the highest of the Statcast zone, as umpires need to take the batter’s stance into consideration, however Statcast doesn’t. All of that is to say that the highest of the zone is the place umpires need to train essentially the most judgment. This season, for the primary time ever, it’s the place they’re least correct.
Under is a warmth map whereby I attempted to point out the likelihood {that a} pitch within the shadow zone could be referred to as a strike. This consists of each shadow zone take from March and April in each 2024 and 2025. The darker the pink, the extra possible a pitch was to be referred to as a strike.
On the perimeters and on the backside of the zone, it’s clear that issues have tightened up. The perimeters are much less unfold out and the reds are extra intense. However the prime is a totally completely different story. If something, it’s extra unfold out. The sunshine pink portion on the prime reaches greater. The darker portion isn’t as darkish, and it pushes decrease. Umpires have been much less constant up there. They’re calling each decrease and better strikes on the prime of the zone. It’s simply plain messier. Nevertheless, in case you break issues down by Statcast’s assault zones, the general image couldn’t be extra clear. The diagram under reveals the change in referred to as strike fee from 2024 to 2025. A blue zone and a destructive quantity means umpires usually tend to name balls. A pink phase and a constructive quantity signifies that umpires usually tend to name strikes, however you don’t actually need to fret about that. There aren’t any pink segments.
There’s no pink on this chart in anyway. The most important features got here on the backside of the center zone, however they have been on the order of a pair tenths of a share level. It is a very blue chart and the corners are the darkest. The zone has undoubtedly shrunk, and all of the catchers and pitchers arguing that they’re dropping strikes have an actual level. As Patrick Dubuque famous at Baseball Prospectus, the league’s stroll fee has elevated.
In a means, it’s exhausting to think about this adjustment in umpiring going some other means. As I attempt to wrap my head across the modifications we’ve seen to this point, I preserve pondering again to the primary graph I confirmed you.
I’ve been making variations of this graph for years, and I believe it says rather a lot about what umpiring is definitely like. It’s simply plain simpler to determine a ball than it’s to determine a strike, and that’s going to be true irrespective of how correct umpires get. The zone has at all times been one thing of an oval, and whereas the corners have tightened up significantly over time, they’re by no means going to get completely crisp. Tightening it up this season has predictably resulted in additional balls, and to some extent that bias has disguised the truth that umpires are off to essentially the most correct begin we’ve ever seen.
