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):

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

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In pitching, there’s a fundamental tension between the two best results you can obtain: strikeouts and grounders. Strikeouts are obviously the best, but grounders are incredible too. Batters put up a .232 wOBA when they hit the ball on the ground, as compared to .462 in the air (popups are another category of good batted ball, but I’m lumping them in with aerial contact today for simplicity’s sake). The thing is, the pitches that induce strikeouts tend not to induce grounders, and vice versa. Sinkers don’t miss bats, and four-seamers don’t keep the ball on the ground. It’s quite the bind.

There are, of course, pitchers who can do both. Nolan McLean springs to mind. There’s peak Zack Britton, Framber Valdez at his curve-spinning best, some good Cristopher Sánchez games perhaps. For the most part, though, it’s really hard to do both. I came up with a simple rule to measure how good pitchers were at it last year: divide grounders by two, add strikeouts, subtract walks, and divide by total batters faced. Aroldis Chapman, Jhoan Duran, and Andrew Kittredge paced the league in it last year, with Shohei Ohtani and Mason Miller rounding out the top five. Those guys were all incredibly effective.

It’s early in the season, of course, but do you know who’s leading baseball in this ratio in 2026? Well, it’s Mason Miller. Oops. I guess breaking baseball will do that. If you’re striking out 70% of the guys you face, of course you’ll lead this measure. But the only other player above 50%? That’d be Riley O’Brien, the new Cardinals closer, who has been one of the best stories in baseball so far this year. Read the rest of this entry »

There hasn’t been much joy in Mudville Queens so far this year. The New York Mets have stumbled hard out of the gate and currently hold the worst record in the National League. That’s far from what was expected before the season, when they were among the betting favorites to win the World Series. You know all that, undoubtedly. We’ve written about it, as have others. But despite that rough start, it’s not all bad. Mets fans also get to experience my favorite thing in baseball so far this year: thinking along with Nolan McLean as he pitches.

McLean is the kind of pitcher you’d design in a lab if your main goal was sheer whimsical delight (he’s also incredibly good, of course). He imparts a ridiculous amount of spin on the ball, which means his pitches move like they have a tiny rocket booster activating midway to home plate (or a minuscule amount of astrophage, for the Project Hail Mary fans out there). Here’s a visual representation of that in our Paired Pitches tool:

It’s actually hard to fit more than one of McLean’s pitches in the strike zone at the same time. His curveball moves more than any other in baseball, with a comical 48 inches of separation from his sinker. His sweeper isn’t far behind; it breaks to his glove side by 21 inches, while his sinker fades arm side by 18 inches, a 39-inch horizontal gap. Home plate is 17 inches wide. You can do the math. Read the rest of this entry »

The book on Munetaka Murakami was pretty straightforward when he hit the market this winter. Phenomenal cosmic power – itty bitty contact rate. While acknowledging recent injuries, our writeup noted his contact rates against good velocity (63%) and secondary pitches (50%) as red flags in his profile. And these weren’t little red flags, either. As Eric and James put it, “…if Murakami is only ever the quality of contact hitter we’ve seen the last three years, with no changes or improvements, he basically can’t be a good MLB hitter.”

Through a month of play, Murakami has been a very good MLB hitter, with a 153 wRC+ driven by a 21.5% walk rate and eight homers. But he’s struggled with contact, and that’s putting it mildly. He’s striking out a third of the time so far, with the fourth-lowest contact rate in baseball through Sunday’s action. So what can we say about that? One answer is that it’s too soon to say – either his contact rate will go up or his production will go down. But that’s pretty unsatisfying. To be fair, it’s probably right, but that doesn’t make it satisfying. So let’s break his game down more granularly to see where the whiffs are coming from, where the power is coming from, and how the two are related.

We’ll start with the “can’t hit secondaries” part of the scouting report. In the early going, that has been abundantly clear. Sixty-six batters have swung at 25 or more sliders this season. Murakami’s 59.3% whiff rate is the third highest, behind Max Muncy The Younger and James Wood. If you broaden that out to all secondaries, 201 batters have offered at 50 or more secondary pitches this year. Murakami’s 53.3% whiff rate is the third highest of that group, behind only Matt Wallner and Daniel Schneemann. Read the rest of this entry »

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Another week, another delightful slate of games, which can only mean one thing: It’s time for another edition of Five Things I Liked (Or Didn’t Like) In Baseball This Week. One of my favorite parts of the early season is rediscovering the small pleasures of watching baseball that I’ve forgotten over the winter. I don’t mean watching Shohei Ohtani and Aaron Judge play. That’s obviously very enjoyable, but it’s not something I forget about in the offseason. But the feel of the game, the look on players’ faces when something unexpected happens, the pure happiness I get from seeing a bunch of grown-ups throw a ball around for a job? I only have that experience when the games are on, and the feeling is strongest after a prolonged absence. So no stars today, just stuff I watched that gave me a happy (or, in one case, angry) feeling. As always, a shout out to Zach Lowe of The Ringer, who popularized this article format in his seminal basketball column. And a programming note: Five Things won’t be appearing every week this season, to help balance out my workload and allow me to work on other projects here at the site. I’ll likely be off next week – unless the baseball I watch this weekend is just too enjoyable not to write about.

1. Late-Night Hijinks
I associate West Coast games with wackiness. It’s likely because I grew up out East, and was usually halfway asleep and fully loopy when I turned on late-night baseball (or late-night any sport, really; I have fond memories of silly Pac 10 football games at 1 a.m.). But there’s something thrilling about the last game of the day’s slate going into extra innings, whether you live in Portland, Maine or Portland, Oregon. Last week, the Padres and Rockies did their best to deliver. Read the rest of this entry »

Entering the 2023 season, Taj Bradley was the no. 36 prospect in baseball, a 22-year-old ace who overmatched his opponents to such a degree that he forced himself to the majors for the back half of the year.

In 2025, Taj Bradley was traded straight up for Griffin Jax, a 31-year-old reliever who has accrued exactly zero wins above replacement for the Rays since that trade.

In 2026, Taj Bradley has been one of the best pitchers in the major leagues.

That’s some roller coaster. And while my first instinct is to take Bradley’s first four starts with a giant grain of salt, this isn’t your average “random dude has good stretch” story. Bradley truly is one of the most dynamic pitchers in the world. He’s electric on the mound. He wasn’t a 55-FV prospect by accident. So let’s take a look at what he’s changed, what he hasn’t changed, and whether this recent run of dominance looks like the portent of a new skill level or just a blip on the graph. Read the rest of this entry »

The normal flow of a baseball season inevitably includes injuries. The dog days of summer usually come with a star or two on the shelf. It’s a long year, and roster depth matters more and more as the months advance. But sometimes, injuries don’t occur at predictable intervals. Sometimes it’s April 14 and half your roster is on the IL. Just ask the Astros.

On Monday, Houston placed Tatsuya Imai and Jeremy Peña on the IL. That followed two moves from last Friday, when Cristian Javier and Jake Meyers both hit the IL. Five days before that, staff ace Hunter Brown landed on the IL himself with a shoulder strain that will keep him from throwing for at least two weeks, and likely prevent him from appearing for far longer than that. And that’s just the in-season injuries. Josh Hader, Zach Dezenzo, Bennett Sousa, and Nate Pearson all started the year on the IL. Brandon Walter, Ronel Blanco, and Hayden Wesneski are still working their way back from elbow injuries sustained in 2025. That’s 12 players on the IL if you’re counting at home, and a number of stars among them.

It’s not like every injury matters the same. Pearson has never appeared for the Astros and has a negative career WAR. Dezenzo is a fifth outfielder. The core missing names for Houston are Brown, Imai, Peña, Hader, Javier, and, to a lesser extent, Meyers. If the Astros can’t replace the production from those five, all of whom are key parts of their roster, 2026 will be a long year. So let’s consider how each affects Houston’s prognosis in isolation, and then consider them all in concert.

Peña’s injury is the one the Astros are best-equipped to deal with. Thanks to last season’s Carlos Correa trade and a quiet offseason, Houston came into this year with an infield logjam. Peña, Correa, Isaac Paredes, and Jose Altuve gave the team four good players for only three spots. None could reliably flex to DH because of the presence of Yordan Alvarez. Altuve spent some time in the outfield last year, even before Correa arrived. Read the rest of this entry »

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