The Strike Zone Is Shrinking. Here’s How.
With the advent of the ABS challenge system, the definition of the strike zone has been laid out with new precision. MLB defines the new ABS zone as follows: “The strike zone will be a two-dimensional rectangle that is set in the middle of home plate with the edges of the zone set to the width of home plate (17 inches) and the top and bottom adjusted based on each individual player’s height (53.5% of the batter’s height at the top and 27% at the bottom).” That’s a change from the way that the strike zone had been understood since 1996. Per MLB.com, that zone was “the area over home plate from the midpoint between a batter’s shoulders and the top of the uniform pants – when the batter is in his stance and prepared to swing at a pitched ball – and a point just below the kneecap. In order to get a strike call, part of the ball must cross over part of home plate while in the aforementioned area.” Those two zones are different, clearly, and it’s reasonable to assume that they would have different sizes and shapes. But how different?
Before the season, estimates of how the zone might change ball and strike calls abounded. We’ve heard anecdotally that pitchers think it’s smaller, and that hitters think it’s taller. But I haven’t seen any studies that attempt to measure it empirically, so I set out to do so.
I’m going to bore you with plenty of math in this article, so let’s start with a few pictures before we dive into the details. I measured a 50% called strike probability border, normalized by player height, using 2025 and 2026 data. The zone has gotten lower and smaller:
That zone considers righties and lefties together. Break it down by handedness, and you get a similar result:
The upshot is that the strike zone has shrunk by around 14 square inches for a 6-foot tall batter, from roughly 454 square inches to 439 square inches. This finding matches the direction of the result that MLB expected to see before the season, if not the precise magnitude. In their ABS explainer, they approximated the strike zone in 2-2 counts as being 449 square inches with the old human-called strike zone and 443 square inches with the new ABS zone.
Now that I’ve given you my top-line findings, let’s get into the methodology. First, I took all the pitches that were called balls or strikes during the 2025 and 2026 seasons. I only considered batters who appeared in both seasons so that I could use their official measured height; I used their official height in 2026 for both years to ensure a consistent sample. Then, for each pitch in each year, I normalized vertical location by height. In other words, a 3-foot high pitch thrown to a 6-foot tall batter would receive a value of 3/6 or 0.5, while a 3-foot high pitch thrown to a 7-foot tall batter would receive a value of 3/7. In this way, I produced a height-normalized form of measurement that is consistent between the past two years, rather than using relative distance from a rulebook defined strike zone. This let me compare like for like — not the area of the strike zone relative to the rulebook in each year, but the true (height-normalized) size of the zone in each year. This is especially important because the exact definition of the zone and the way the zone is called have not always correlated perfectly; in fact, despite no change in the rulebook zone, changes in umpire evaluation have moved the strike zone borders around in recent years.
I took all the normalized pitch locations in my remaining sample, and then I further restricted it by time. I used only pitches that were thrown through April 25, 2025 last season, and through April 25, 2026 this season. I’m not sure whether there are any hidden calendar effects to strike zone size, but I didn’t want to take any chances; this methodology relies on comparing a like zone, and this time restriction still gave me plenty of data. After all, the limiting factor here is the fact that the 2026 season is still incomplete, and I haven’t dropped any of that data.
With these called balls and strikes in hand, I transformed the individual calls into a probability distribution using Nadaraya-Watson kernel regression. In layman’s terms, this is a bin-and-smooth technique. It works by creating a grid, 121×121 in this case, and then placing each pitch into those bins. It then smooths each pitch’s location using a Gaussian filter and calculates the smoothed called-strike probability in each zone. Those called-strike probabilities are used to create the frontier of the 50% called-strike-probability zone, which I’m using to define “the strike zone” for this study. I used the 50% called-strike rate as the border because that matches the on-field experience of the strike zone. For everything inside this border, an umpire is more likely than not to call a strike. For everything outside it, they’re more likely than not to call a ball. Given the inherent uncertainty of the zone as called by humans with occasional robot assistance, I think this is a definition that comes closest to matching how the zone feels to players. As a bonus, it’s also the standard definition used by many seminal studies of the strike zone.
Using this method, I estimated the size and shape of the strike zone in the past two seasons. For example, the top of the strike zone for a 6-foot batter in 2025 was roughly three feet, 5.5 inches. The top of the strike zone for a 6-foot batter in 2026 has been roughly three feet, 4.5 inches. The bottom of the zone for that 6-foot batter was roughly one foot, six inches in 2025; it’s been roughly one foot, 5.5 inches in 2026. There was no meaningful change in the width of the strike zone, as you’d expect; that’s defined by the width of home plate, which has not changed.
To determine whether these changes were statistically significant, I calculated bootstrapped confidence intervals. To do this, I broke my sample out by game and then picked games at random, with replacement, to form new samples for both years. I repeated this process 100 times. I took the 2.5th-percentile and 97.5th-percentile results of the bootstrap to form confidence intervals, both for the size of the zone and the change in the size of the zone. Those results are as follows (reported for a 6-foot batter):
| Metric | 2025 | 2026 | 2.5th Pctile Change | 97.5th Pctile Change |
|---|---|---|---|---|
| Zone Top (ft) | 3.448-3.475 | 3.369-3.396 | -0.067 | -0.033 |
| Zone Bottom (ft) | 1.514-1.541 | 1.461-1.488 | -0.033 | -0.017 |
| Zone Width (ft) | 1.725-1.775 | 1.7-1.725 | -0.075 | 0 |
| Zone Height (ft) | 1.921-1.961 | 1.881-1.922 | -0.079 | -0.012 |
| Zone Area (sq. in) | 448-460 | 435-442 | -22 | -8 |
I interpret this as saying the following: The top of the strike zone is lower. The bottom of the strike zone is also lower, though by less. The width of the zone may be very slightly smaller, though it’s hard to say. The total area of the strike zone has declined, likely by between eight and 22 square inches, somewhere between 2% and 5% of the total strike zone area.
Another form of analysis proved more difficult: determining the changing shape of the zone in different counts. There’s a two-fold problem here. First, the sample sizes of the raw pitches thrown in each count are far smaller than they are for the overall population. Second, we’re looking for zones of the plate where strikes are called roughly 50% of the time so that we can perform boundary analysis, but batters don’t take a lot of 50/50 balls in certain counts. Look for a cluster of pitches in a 1-2 count that didn’t produce a swing and yet had a 50% chance of being called a strike, and you’re going to be looking for a while. Batters don’t take those pitches.
However, I was able to cobble something together with a little help from our extensive library. The PitchingBot model produces estimates of the likelihood of a swing for every pitch. I used those estimates to create an inverse probability weighting for each pitch. The less likely a given count/location/pitch type combination was to lead to a take, the more I weighted it in our sample. This statistical method corrects for the sampling bias inherent in looking at only pitches that a batter took.
This method produced two interesting takeaways. First, the strike zone in three-ball counts hasn’t really changed, even while everything else has shrunk. Umpires are in fact calling a slightly larger strike zone in counts with three balls, though it’s statistically indistinguishable from the 2025 zone in the same counts. Second, the old effect of umpires tightening the strike zone in two-strike counts is vanishing. In zero-strike counts, the 2026 strike zone is 8% smaller than the 2025 strike zone. In two-strike counts, the 2026 zone is 1% smaller than the 2025 zone. I’m not confident in this effect size, thanks to the fact that I cut sample sizes down significantly by bucketing by count, but I am confident that an effect exists.
I do not feel confident in making any strong claims about the downstream effects of these changes. This study was set up particularly to measure the size of the zone, not to consider how pitcher and batter behavior have changed as a result. That said, it’s certainly suggestive that walk rates have increased. It’s even more suggestive that the called strike rate for fastballs just above the borders of the ABS strike zone, 53.5% of a batter’s height, has declined markedly. In 2025, fastballs thrown within the width of home plate and between zero and four inches above that 53.5% cutoff were called strikes 54.3% of the time. So far in 2026, pitches thrown to that area have been called strikes 40.8% of the time.
Another interesting effect: ABS challenges themselves aren’t having much effect on the size of the zone. I took all challenged calls and reverted them to the original umpire call, then re-ran the entire model. The difference was minimal; using pre-challenge calls, the zone has shrunk ever so slightly more than the measured effect reported in this study, though not by a statistically significant amount. The net effect of challenges is quite small. Here’s a graphical representation of the difference between the as-called zone (using the final result, post-challenges) and the zone assuming no challenges were allowed:
None of this is settled science. The zone will continue to evolve as batters, pitchers, catchers, and umpires adjust to the new rules. The definition of the strike zone isn’t set in stone – obviously so, given that the zone was called in three dimensions last year and is called in two dimensions in 2026. There are meaningful downstream behavioral implications, too, and I expect league-wide walk rates to decline as pitchers adjust to the new strike zone. But so far, pitchers’ reports of the zone are correct: The strike zone, as called by umpires and the ABS challenge system in 2026, covers less area than it did in 2025.
Appendix A: Data
The data and Python code used to prepare the principal analysis in this article are available here. This code covers the method for normalizing pitch locations, constructing normalized pitch plots, measuring the difference between the two, bootstrapping confidence intervals, and separating results by handedness. A markdown document explaining the function and design of the Python code is also available at that link. Further documentation is available as needed. I’ve left out anything that uses internal-only data, like PitchingBot model values, but I’m happy to discuss specific methodology further on a one-off basis.
Appendix B: Further Reading
I linked to several articles about the changing shape of the strike zone in 2026 at the top of this article. The following is a more complete bibliography of sources who have written about the size of the zone in the ABS era:
- “How MLB’s Ball-Strike Challenge Will Change Baseball,” Peter Abraham, Tim Healey, Alex Speier, John Hancock, and Daigo Fujiwara-Smith, The Boston Globe
- “Players Say Robot Umpires Are Shrinking MLB’s Strike Zone,” David Brandt, Jay Cohen, et al., The Associated Press
- “Everything You Need To Know About The New ABS Challenge System,” Anthony Castrovince, MLB.com
- “MLB’s Switch to ABS Shrunk Nearly Every Hitter’s Strike Zone,” Mike Emeigh and Reddit
- “Jose Altuve’s New Strike Zone,” Jarrett Seidler, Baseball Prospectus
- “MLB Made a Change That Players Say Shrank the Strike Zone,” Jayson Stark, Ken Rosenthal, and Eno Sarris, The Athletic
- “ABS Has Shrunk The Strike Zone; Walks Are Spiking As Hitters Try To Adjust,” Cody Stavenhagen, The Athletic
- “ABS Challenge Rates By Proximity to Border of Strike Zone,” Tom Tango
- “Lefties Eat Hot Dogs, Righties Eat Burgers,” Matthew Trueblood, Baseball Prospectus
- “Yes, MLB’s Strike Zone Is Shrinking. But Baseball Will Be Better For It,” Tom Verducci, Sports Illustrated
- “This is Not Even The Strike Zone’s Final Form,” Bradley Woodrum, Baseball Prospectus
Ben is a writer at FanGraphs. He can be found on Bluesky @benclemens.
Why did MLB choose to make the strike zone a two dimensional rectangle in the middle of the plate instead of a three dimensional irregular pentagonal solid? Is the pitch tracking technology incapable of dealing with a three dimensional strike zone?
Because it was never called that way.
The explanation I’ve seen is that the three-dimensional version (or the version at the front of the plate) was calling pitches that most observers agreed should not be strikes as strikes. Breaking balls that end up in the dirt but brush a corner of the zone, that kind of thing. That was deemed undesirable, so they changed it.
Minor league tests. They tried front of the plate, back of the plate and all at once (iow 3D) and found that the zone that most closely matched the zone of the past and the expected zone was to use the 2D mid plate zone. This prevented the bouncing curves catching the front bottom or the looping curves catching the back top.
I understand the reasoning, but I would prefer a ‘three dimensional irregular pentagonal solid’. I think the zone would need to be changed for this to work, but I think it would incentivise teams/pitchers to value control more than they currently do. Imagine a pitcher who only throws mid to high 80s but can bury curveballs in the dirt for strikes, or graze the top back corner/edge of the zone consistently. Opens the field for more potential pitching styles….assuming those advantages can counteract the advantage of throwing really really hard
Your thinking is coherent and your idea is valid, so it will of course be voted down here. This is a groupthink only area. Anything that you value regarding individual skill–outside of flipping a bat or hitting homeruns, which is celebrated–or athleticism that involves physical contact, will be discouraged or shot down as blasphemy.
Alright everyone, the jig is up. I don’t know how they managed to piece it together, but these intrepid Internet detectives have exposed our vast 2D strike zone conspiracy. Although our Planar Putsch has successfully occupied the MLB rulebook, we must remain vigilant against the counterrevolution
Shouldn’t you be out on a ledge somewhere?
And people think *I* have bad takes….
I don’t think those advantages would counteract the advantage in throwing harder with much less command – the guy with 30 control but a 98mph FB with movement and a wipeout slider gets the bigger zone too.
Though, it would be fun if the slower you threw, the bigger the zone (so 1% bigger for each mph below 95mph, 1% smaller for each mph faster). Obviously this would require full ABS – and would it per pitch/based on the pitchers average velocity per pitch type/fastest pitch that season/last 30 IP.
It would be a blip. A season or three where batters had to learn the new boundaries. Then we’d be right back to pitchers chasing velocity and batters chasing high velocity pitches
I dunno, I think that might just make for bad baseball. Assuming you could develop these magicians, wouldn’t their pitches be more or less impossible to hit, especially with any authority?
If the main effects are a lower top and bottom, how much of this is the much-mocked change in official player heights? If you reran the numbers using the published heights of players in each respective year (imagining those changes in official heights to be real, say), how much of this effect vanishes?
Presumably the umpires didn’t know the listed heights for each player in either year. They weren’t giving Alex Bregman the zone of a six footer just because he used to lie.
They certainly play a role this year thanks to ABS. But I also don’t think it’s so inconceivable that they could have played a role last year. For instance, post-game reports (i.e. whatever professional equivalent there is of the Umpire Scorecards Twitter account) could have used batters’ listed heights to calculate missed calls, and umpires looking to improve could have adjusted off of that information to call a generally higher and larger zone than they otherwise would have.
Thank you for including the github repository for those of us who can’t get enough
Great work, Ben! As usual.
I had to laugh at ‘Gaussian filter’. Whatever you do, don’t call it normal.
Sounds fancier this way, though! And Nadaraya-Watson kernel regression is a personal favorite ‘ooh, sounds neat’ one as well.
Don’t you dare laugh at Gauss! He’s (arguably) the G.O.A.T. of math.
It would have to be between him and Euler, right?
Rene Descartes and Alexander Grothendieck have strong cases as well.
His splitter is pretty good too.
I’m just glad there’s a publicly defined strike zone the umps have to stick to. They’ve been doing a really impressive job now that they’re not calling what they think the zone should be.
This is very interesting. Thank you for putting this together, Ben! My much less sophisticated analysis (which, admittedly, was more focused on strike zone width) suggested a taller zone this season. That was a few weeks ago. Perhaps the data has changed, or perhaps I had glitches in my zone normalization.
I think one of the key questions, which others have alluded to, is what is the impact of more accurate heights on our zone data? I know players were getting measured last year, but we still had several big changes this season. The zone can appear “taller” if you report your height as 5″10′ but the umpire is calling a zone for an actual 6″0′ batter standing in there. But few hitters would have exaggerated their heights in that direction, no?
Thanks, Bradley! I appreciate the kind words.
As to measuring with the old heights, I don’t think I get the idea, to be honest. I used 2026 heights so that I could compare batters to themselves. If I want to know the physical height of Alex Bregman’s strike zone in each year, I want to use the same measurement for Alex Bregman’s height in both years. Otherwise I might run into issues where for the same actual physical size of the zone, I don’t get that as an answer.
Imagine that Bregman listed himself at 6’0″ last year, and 5’10” this year. Imagine, also, that I calculated his strike zone as going from 1.5 to 3.1 feet in both years. The correct conclusion in terms of the called, on-field zone is that Bregman’s zone didn’t change. But if I used different height data for different years and continued to normalize by height, I’d see a difference. That’s why I plugged 2026 data in for all players.
As it turns out, it’s hard to get a complete set of 2025 height data anyway, but that’s not the reason I chose not to use it. I just didn’t think it was the right metric.
I answered a similar question a minute ago with a similar answer, and what’s funny is that I also used Bregman as my example. Apparently he’s the poster child for height-liars.
Are they actually measuring the players? Because he doesn’t look 5’10” either… maybe 5’9” on a good day
They let him get measured with his cleats on?
The idea is that if some umpires were attempting to align their calls with any automatically calculated zone before, like by reviewing a list of their missed calls after each game, any such systems, like ABS, would likely have used listed player heights. I know the stereotype is that all umpires were only ever using what they can see with their own two eyes, but I’m sure that MLB would have given them some kind of tools to help, given that they have the data. And any such tools would have been using the old heights.
In terms of game enjoyability the ability to challenge helps.
In terms of reducing the percentage of runs scored via solo HR it probably doesn’t matter. To me that’s the least entertaining mode of offense. But I’m old and obsolescing
First time I have ever heard that ABS might be a method of reducing runs scored via solo HRs. Doesn’t even seem like something possible, or desirable, to structurally prevent
I shouldn’t speak for Ivan, but I don’t think he was saying that was the intent or goal of ABS. I think he was suggesting that if MLB was going to be changing anything, they should focus on reducing the things that cause a lot of solo HRs (high strikeouts, fewer balls in play, lower BABIP when balls are put in play, launch angle revolution, etc). That would increase his enjoyment of the game (probably mine too).
Me, fantasy baseball player: I understand statistics
Me, reading the paragraph about Nadaraya-Watson kernel regression: I do not understand statistics
This was an obvious outcome to anyone paying attention to AAA results the past couple seasons as ABS was refined, and everyone – umpires/hitters especially – adjusted their behavior accordingly. Umpires MUST call a tighter zone, because by rule definition, IT IS TIGHTER. Walk rates are up significantly, and they probably won’t go down – unless pitchers begin to “give in” (by throwing more pitches in zone, closer to the center), and then offense will spike.
Another point that teams SHOULD begin to learn from (pitchers/catchers): is that umpires ARE calling a tighter zone first pitch and zero strikes, therefore, those are the pitches that are low-hanging fruit and should be challenged more as the difference in OPS after 0-1 vs 1-0 is significant.
I dunno, I don’t want my hitters, pitchers, or catchers burning challenges on a first pitch when I would be better served getting a walk on a 3-ball count (as a batter) or a strikeout on a 2-strike count (as a pitcher).
I would love my opponents to burn through theirs on erroneous challenges on 0-0 counts however.
“Those two zones are different, clearly, and it’s reasonable to assume that they would have different sizes and shapes.” Well, not really. Yes, they are different. But as defined they are both the same shape: rectangles. And they are both the same width: the width of home plate, which hasn’t changed. The height definition has changed, but that ought to affect different players differently (e.g. Altuve, whose crouch theoretically reduced his strike zone previously and now has to protect for his full height (previously listed at 5’6″, which may not be his ABS height)).
There are three strike zones that need to be distinguished: 1) the defined strike zone; 2) the ABS strike zone (which ought to be close to identical to the newly defined strike zone); and 3) the strike zone called by the umpires. The data analyzed here is mostly from set 3, with the exception of the small percentage of calls overturned by ABS. But the observed changes are not a change in the strike zone itself, they are a change in the way pitches are called by the umpires. The fact that the strike zone is statistically different depending on the count shows that many of the observed differences are the result of umpiring inconsistencies (no perjorative intention to be critical of the umpires): ABS doesn’t know the count and even if it did, it would call pitches identically no matter the count.
So the data analyzed here show that umpires have been calling a different and smaller strike zone. Some of that may have to do with the change in the strike zone definition. But it is likely that a lot of it is the knowledge that their calls can be challenged and they are trying to hew more closely to the definition of the zone. This is supported by one of the most interesting (to me) statistical develolpments in ABS: more ball calls have been changed by ABS to strikes than strike calls changed to balls. Sixty percent of ABS overturned calls are ball calls changed to strikes. (Data source: Statcast). Since I, and I think many people, in the past thought umpires called a wider zone than the former defined strike zone, one might have expected more strikes being overturned to balls. There may be other explanations for this observation: only hitters challenge strike call, while both catchers and pitchers may challenge ball calls (54% of challenges have been to balls) and so far catchers seem to have the best sense of the three of when to challenge. Also, it is still April, and the system is brand new, so all ABS analysis could significantly change over time (which is worth considering when doing any analysis of strike zones or ABS at this point). .
What this analysis does show is that some meaningful percentage of pitches that would have been called strikes last season are now being called balls. Some of that is likely a result of the change in the strike zone definition, but certainly not all of it, and probably not even most of it. That is probably a good thing. While the width of strike zone is defined as the 17″ width of the plate, it effectively is almost 23″ as the diameter of a baseball is just under three inches and one needs only to have a sliver of the ball cross the plate to get a called strike. That ought to be enough for pitchers to work with.
The “strike zone” has always been whatever the home plate umpire calls that day.
And, we are talking about human behavior; game theory is and always has operated: no matter how bad the call 0-0, all of hitter, pitcher, catcher know the AB is not over.
Lastly, YOU try throwing a baseball 60’6” to a target that small, and then tell me if you have “enough to work with”.
When you look at the oval-shaped zones above, it’s easy to see how the system results in contradiction between spirit and letter of the law. There’s a goal of making “correct” calls as defined but, historically at least, there’s also a goal of consistent application.
Over the course of a game, say an umpire calls 9 pitches balls in which a molecule of the horsehide ticks one of the four zone corners. No one challenges because the pitch sure looked like a ball and challenges are precious. All 9 calls may have been technically incorrect, but the umpire’s consistent application meant both pitchers and hitters fairly knew how to act within the given parameters. Then in the 9th inning, with nothing to lose, a catcher challenges such a call and has it overturned to a strike. The letter of the law credits ABS with getting that call “right,” but wasn’t the batter conditioned at that point to wisely not offer at such a pitch? At the game’s most pivotal points, the application of the practical strike zone suddenly changes.
By introducing inconsistency, an ABS reversal can inadvertently accentuate the negative impact of those first 9 calls more than warranted. In my mind, the ABS reversal becomes the “wrong” call in this (admittedly somewhat extreme) scenario.
That’s not to imply that I dislike ABS. Personally, I would love to see MLB shave and round off the corners of the ABS zone so that it more closely mirrors what umpires have been calling for decades. Since the zone was created to force pitchers to throw pitches in hittable locations, an oval shape is logical and preferable (to me).
Well said, amen!
Uncertainty and inconsistency always exist on borderline calls. Always have. As discussed in this article, umpires zones change based on the ball/strike state. They also often change from one moment in the game to another, even if there is no intent. We have all seen a pitch called one way in the 2nd inning and the same pitched called differently in the 7th. If a batter decides to assume the first call was the truth ever-forward, he’s likely to be burned later. ABS doesn’t change this.
To me, the solution to this is to give the home-plate umpire an earpiece that relays the ABS call in real time, and he simply echoes it for the players on the field.
We have redefined the strike zone to be consistent with ABS (and still give results similar to the zone in recent history). Why, if the zone is defined for ABS, are we not simply using ABS? This doesn’t eliminate the homeplate umpire or his job, but it does eliminate the impossibly difficult job of trying to duplicate what a computer is doing and being graded on how close you can come to the computer, but not simply using the computer.
Processing time. In those seconds between the pitch, the umpire’s call, and the player’s request for the challenge the robots have time to make <i>their</i> call. But if we had to wait for that on every pitch the delay would be very noticible.
But then we can all enjoy the pregnant pause before the umpire gives an Enrico Palazzo style
………………………………………………………………………………“strike?”
I was prepared to hate your comment. But, yeah, why not define an oval zone? I’ve been impressed with how close the umpires are getting even when overturned (except that one Refsnyder strike call that was almost 6” outside of the zone).
Could there be an “Angel Hernandez Effect” occurring where umps with larger zones last year are no longer working games this year?
My prior comment got eaten because I edited it too many times trying to get the formatting right, so I probably missed my chance to have Ben see it, but oh well, here goes…
If one were to create a “2025 rulebook” gray dotted box in the graphic, would it be different from the “2026 rulebook” box?
Using the Baseball Savant queries, the proportion of pitches defined as “in the zone,” i.e., zones 1-9, that were called balls has gone from about 13 percent to something in the single digits, a la seven percent (I had the numbers before my misadventures with the filter…). The rate of out-of-zone pitches called strikes also decreased, but relatively slightly.
If the 2025 rulebook and 2026 rulebook zones are consistent, this raises a weird question vis-a-vis the zone shrinking using the measurement-in-feet-and-inches data. If they are not consistent, then this explains it, but raises the question of what exactly happened between the 2025 and 2026 rulebook zones…
That’s a question for the Baseball Savant team. I can tell you that the values of sz_top and sz_bot are not identical for the same player between 2025 and 2026, and that in 2025, that value varied from one pitch to the next (though not always. Like I said, it appears to be complicaated), while in 2026, it’s the same value for every pitch. I do not see any formal documentation of exactly how those values are calculated, but that’s why I was so careful to measure the zone physically, using only verified player heights and actual pitch locations, and without any regard to what is deemed ‘in’ and ‘out’ based on a strike zone whose definition is not known to me.
I truly appreciate the reply.
This creates a somewhat weird cross-year comparison, because the league zone rate has cratered according to the Baseball Savant data from 2025 to 2026, by far more than would be suggested by your visuals.
I was already basically using z-scores for everything, but they’re going to be inescapable now with such “big” swings in league plate discipline stats that revolve around definitions of what is/isn’t in the zone.
THIS IS AN INCREDIBly Elegant and phenomenal ARTICLE!! This type of article is what makes FanGraphs the paragon of baseball analytics analyses. Congratulations, Ben!
Super interesting – and thanks for posting the code!