The Secret Stance Adjustment That Unlocked Jackson Chourio's Offense in 2024

[Matthew Trueblood]

Statcast offers the public data on how batters set up and address the baseball now. It's a frontier for numbers nerds, but also a new world of opportunity to discover hidden aspects of the game.

Image courtesy of © Rick Scuteri-Imagn Images

Early in 2024, Jackson Chourio was in trouble. It wasn't all that bad, really. He'd already signed a contract worth over $80 million, and the Brewers had promoted him to the majors after just a handful of looks at Triple-A pitching. Everyone would understand if he needed more time in the minors—and even that wasn't necessarily imminent. As the rookie limped from a lousy April and was mired in a mediocre May, though, his playing time began to dwindle. He needed to start getting after big-league pitchers with the same confidence and explosiveness that sent him skyrocketing to the parent club in the first place.

So, he spread out a little bit.

As of Sunday night, Baseball Savant offers new data on where players set up in the batter's box; how they move throughout their swing; and where they tend to make contact with the ball. It's long-awaited information, some version of which teams have been using for years, and it's a kind of culmination of the third wave of sabermetrics. The first goal for statheads was to convince baseball people to care about the right things—to draw the proper chains from cause to effect and finally learn how baseball games are actually one. In the second wave of the movement, though, a wealth of new information became available, challenging those math geeks to do something impressive with them. Tabulated data on how defenders were deployed, pitch-by-pitch outcomes, and even the movement of the ball in space came relatively quickly, one after another, and smart people who wanted to keep sounding smart had to go from doing basic statistics work to (at times) fairly advanced physics calculations.

Now, we're firmly into a third category. Cameras can map not just the flight characteristics of the ball, but tons of small but crucial details about how the players move, as well. That means that teams can spot mechanical failures, engineer better pitches, and select matchups based on combinations of swing path and pitch shape. It also means that we now get to try out some of our old statistics and arithmetic work on the infinitely nuanced data that are these measurements of player movements.

Chourio didn't make some grand statement, or tweak his setup and swing in a major, noticeable way. He just spread out in the box. For the first two months of the season, his feet were a bit over 37 inches apart, most of the time. That's an above-average number, but a reasonable one. Chourio's stance was fairly standard.

Starting in June, though, Chourio kept his feet more like 41 inches apart. The difference sounds tiny, and in a way, it is. Test it out sometime, though. Stand with your feet about shoulder-width apart, and then carefully slide each foot two inches farther. You can feel that difference, even if someone staring at you might miss it. Ballplayers know their bodies so well that almost everyone sets up with their feet a tiny fraction farther apart—mostly somewhere between 0.5 and 0.9 inches farther. That tells you how finely these people calibrate their sense of their bodies in space—but it doesn't make it easier for us to spot Chourio's. It's just a reminder that he can't have shifted to such a stance by accident.

Well, we were all staring at Chourio from the center-field camera, so it was very easy to miss the subtle change in how he set up. That's no angle from which to spot such a thing. It was there, though, and it mattered.

Here's a video of Chourio from late April, against now-teammate Tyler Alexander.

Here's one from mid-July, after his change in setup and swing.

Once you're looking for it, you can spot it, but you might have said it was almost accidental, or inconsequential. Chourio is a little bit more open in his stance, and he's just a little deeper in his legs. They're spread enough that he needs only a minimal stride to effect his transfer of weight and energy into the ball.

Here's what it looks like on Savant's new, spiffy leaderboard and graphic display. Chourio's stride is so much shorter that he can just attack the ball under more control in August than he could in March and April.

Because his swing was more balanced and his head was more still, Chourio tended not to top or slice underneath the ball, later in the year, but to square it up and get a lot of exit velocity from his bat speed. In turn, that removed some of the pressure to generate that much bat speed in the first place.

I don't mean to sell this as a magic tweak to his stance and stride. It's something less than that. After all, we already knew that the incredible level of performance Chourio provided in the final four months of the season was within his range of possible outcomes. Still, it's noteworthy, because Chourio—just 6 feet tall—set up with his feet farther apart last year than all but nine other qualifying batters. Lop off those first two months, and only seven guys started more spread-out in the box. Some of those guys (Giancarlo Stanton and Oneil Cruz) almost have to set their feet wider than Chourio's, to avoid stepping on their own toes. Yordan Alvarez didn't have his feet as far apart last year as Chourio did. 

It takes an incredible athlete to spread out this much and still generate the torque and the energy transfer required to hit the ball hard—incredible, that is, even by big-league standards. Chourio is freakish even among major-league hitters. His ability to drive forward smoothly without a big timing mechanism or a complicated load is unique. His cocktail of youthful quickness and sheer strength is rare. Spreading out helped Chourio a great deal last season, even if it wasn't the primary reason why he suddenly found his way. It's great that we now have this information, so we can spot more of the small things that make baseball's big things possible.

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[eddiemathews]

Marshall, I will expect you to predict change in results from noticing batting stance changes from here on in. Of course, change isn't always positive...