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 up to now, it’s the inescapable takeaway that umpires are wonderful at what they do. When Main League Baseball launched PITCHf/x in 2008, umpires bought 84.1% of ball-strike calls proper in accordance with the Statcast strike zone. Over the intervening years, whereas ever-nastier stuff and a revolution in pitch framing had made their jobs tougher and tougher, umpires did nothing however get higher. Accuracy broke 92% in 2021 and inched its approach towards 93% over the following two seasons. That pattern of bettering yearly lastly modified in 2024.
As I wrote yesterday, final season marked the primary time that umpires bought worse quite than higher. That’s attention-grabbing sufficient by itself, however proper when it was time to wonder if they’d gotten pretty much as good as they may get, the principles of the sport modified. Over the offseason, a brand new labor settlement included a change to the best way that umpires are assessed by the league. The grading bought 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 rather more tightly. Let’s dive into the numbers and see what appears to be like totally different up to now this season. Right here’s a graph that exhibits total accuracy in each season of the pitch monitoring period.
The yellow line exhibits total accuracy, and it’s ticked again up from 2024. Despite the fact that it’s early within the season, a time when umpires are at their least correct, they’re nonetheless doing higher than they did final 12 months. Accuracy fell from 92.81% in 2023 to 92.53% in 2024, and is now again as much as 92.63%. The truth is, 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 accurately.
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 achieved bettering totally. What pursuits me is the best way the pink and blue traces within the graph above diverged so drastically. The graph under exhibits the impact extra clearly, as a result of it exhibits solely pitches within the shadow zone, inside one baseball’s width of the sting of the zone, the place an umpire’s judgment is de facto examined.
All the best way 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 significantly 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 exhibits 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 charge ever recorded. Right here’s what that appears like in a line graph.
Take a look at the best way that line has shot down this season. Now think about the truth that up to now, 44.9% of these pitches really hit the strike zone, the very best charge in 10 years. Right here’s the identical graph, however with zone charge additionally included.
The zone charge actually doesn’t appear to have any bearing on the referred to as strike charge, particularly this 12 months. This is the reason pitchers and catchers have been telling The Athletic that the strike zone is shrinking. Sure, accuracy has improved, nevertheless it’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 specifically has been disappearing. As a way to study that, I pulled accuracy information on three specific elements of the shadow zone. Let’s begin on the edges 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 high and backside shadow zones. We’ll get to the corners later. The pattern right here has been clear for a very long time.
Umpires have been steadily getting higher on the edges of the plate, and that enchancment has usually 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 total, however they’re lacking extra strikes than they used to. Right here’s one other approach of viewing these traits. The graph under exhibits the typical horizontal location of each ball or referred to as strike in these two zones. The grey space exhibits the precise width of dwelling plate.
As you may 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 true on the sting of the plate. Nonetheless, 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, over time, umpires have gotten extra correct on the backside of the zone by calling extra strikes. The graph under exhibits 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 need to get a way of the place the true backside of the zone is with out letting the edges of the plate have an effect on it.
Over time, the underside of the strike zone has gotten considerably decrease, and catchers across the league have adopted one-knee down stances so as to earn extra referred to as strikes down there. From 2009 to 2020, the peak of the typical referred to as strike on the backside of the zone dropped by 1.92 inches. Nonetheless, ever since, that common has been ticking again up. This season, it’s 0.6 inches increased than it was in 2020. Nonetheless, up to now this season, the impact hasn’t been as drastic as it’s on the sides of the plate, the place umpires have really 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 exhibits 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 a degree. Not solely have umpires been calling a tighter zone up there, however they’ve been calling it so tightly that they’ve really gotten much less correct total.
This graph doesn’t appear to be the others, and there’s a motive for that. The others had straight traces that informed a tidy story. On the edges, umpires have been all the time good at figuring out strikes, and over time they’ve gotten higher at figuring out balls, basically squeezing the zone as they bought higher at discovering the sides of the plate. On the backside of the zone, umpires have been all the time good at figuring out balls, however they steadily improved at figuring out strikes, reducing the zone.
The highest of the strike zone is lots fuzzier than the edges and the underside. Umpires can’t simply look down at dwelling plate to information them visually, and the highest of the zone varies rather more from batter to batter than the underside. Furthermore, the highest of the rulebook zone varies probably 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 probably the most judgment. This season, for the primary time ever, it’s the place they’re least correct.
Beneath is a warmth map whereby I attempted to indicate the likelihood {that a} pitch within the shadow zone can 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 probably a pitch was to be referred to as a strike.
On the edges 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 high is a very totally different story. If something, it’s extra unfold out. The sunshine pink portion on the high reaches increased. 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 high of the zone. It’s simply plain messier. Nonetheless, in case you break issues down by Statcast’s assault zones, the general image couldn’t be extra clear. The diagram under exhibits the change in referred to as strike charge from 2024 to 2025. A blue zone and a unfavourable quantity means umpires usually tend to name balls. A pink phase and a optimistic quantity signifies that umpires usually tend to name strikes, however you don’t really want to fret about that. There aren’t any pink segments.
There’s no pink on this chart in any way. The largest features got here on the backside of the center zone, however they have been on the order of a pair tenths of a proportion level. This can be 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 shedding strikes have an actual level. As Patrick Dubuque famous at Baseball Prospectus, the league’s stroll charge has elevated.
In a approach, it’s arduous to think about this adjustment in umpiring going another approach. As I attempt to wrap my head across the adjustments we’ve seen up to now, I maintain pondering again to the primary graph I confirmed you.
I’ve been making variations of this graph for years, and I feel it says lots 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 all the time 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 probably the most correct begin we’ve ever seen.
