Don’t Call It a Changeup: Jeremiah Estrada’s Chitter Changed His Approach

[Randy Holt]

Ahead of the 2024 season, Jeremiah Estrada was a two-pitch reliever with barely more than 15 big league innings to his name. A year later, he's still a two-pitch reliever. But the pitches — and the volume — have changed.

A former prospect of the Chicago Cubs as far back as 2017, Jeremiah Estrada broke out in 2022 courtesy of a 1.30 ERA across three levels of the minor leagues. That performance earned him a cup of coffee and five big league innings before another dozen appearances in 2023. The latter year didn't favor him nearly as much. His command slipped and the Cubs designated him for assignment by early November. 

The Padres claimed Estrada off waivers four days after his DFA, and Estrada latched onto a regular relief role last year. He didn't just hold onto a roster spot but thrived across 62 appearances and 61 innings in San Diego. He would go on to post a 37.3% strikeout rate, a 9.1% walk rate, and a 2.07 ERA, emerging as a key part one of the better relief groups in the league.

Estrada became something of a sensation courtesy of his "chitter." A hybrid pitch that features a Vulcan grip and characteristics of a splitter and changeup, Estrada began throwing the pitch last year. The Cubs had attempted to get him to throw a splitter, but he was unable to get comfortable throwing it. With the Padres, the chitter was born. 

Because there's only so many times you can use the word "chitter," we'll refer to the pitch as his splitter moving forward (also because that's how Baseball Savant classifies it). And while Estrada's splitter only accounted for 19.8% of his pitches last year, its 51.8% whiff rate was the best among his pitches by more than nearly 20 percentage points. As Estrada adjusted to throwing the pitch, though, he remained primarily a fastball-slider guy. Clearly, given the numbers above and his increasingly crucial role as the season wore on, that worked for him.

This year, however, we've already seen a deviation in his usage from a year ago. The possibility that we'd see the splitter more frequently deployed in conjunction with his fastball and slider always existed. But that hasn't been the case. Instead, Estrada has virtually ditched his slider in favor of the splitter as his no. 2 pitch: 

The rise for the splitter hasn't been tremendous on its own. The pitch is up to 22.6% usage, but when you combine it with the steep drop in his throwing of the slider, his aim starts to become fairly clear. The slider is being thrown just 6.5% of the time this year (with a notable 100% percent whiff rate in those rare instances). 

While the slider was an effective tool for Estrada, it also wasn't an out pitch in the way that we might expect for a two-pitch reliever. He generated a 52.9% groundball rate with it, but there was no discernible difference between the slider and his other offerings in terms of average exit velocity, chase rate, or movement. It just wasn't doing the things you'd really expect a slider to do in terms of outcomes. 

Given how much more effective the splitter was than the slider last season, the shift in usage is logical. Adding to the logic is the fact that he was able to hold opposing hitters to the lowest hard-hit rate (25.0%) among his three primary offerings with that pitch, while generating the highest whiff rate. But with the flip from slider to splitter, an interesting trend has started to emerge. For one, Estrada hasn't generated a single chase with the split. He hasn't garnered one groundball (with the splitter or any other pitch type). There also isn't any hard contact to speak of against his non-fastball pitches. A quick peek at the zone profile tells us what we need to know, though: 

It's too early to know whether this is intentional, but through his first handful of appearances, Estrada is working up in the zone more often. He worked all four corners last year, especially when the slider was involved. Now, it's almost as if he's taking on a plan of attack not unlike Shōta Imanaga in Chicago. It can be effective when properly executed. And it certainly looks as if Estrada's up to the challenge thus far. 

With the fastball, he's been able to generate popups exactly half the time; with the splitter he's getting fly ball contact at a full 100% clip. Hard contact hardly matters (and barely exists) on a popup and the soft contact induced by the splitter minimizes the danger pretty drastically. Estrada has also been inside the zone on 50% of each pitch type. Hitters are going to feel compelled to swing when you're working inside the zone that frequently, and that could be to his benefit as long as the precision remains. 

We're not foolish enough to think that the command will always be precise enough to make this a surefire strategy. It's also much too early in the season to know if this is even intentional; Estrada has only made five appearances as of this writing. But a .080 expected batting average with zero barrels kind of speaks for itelf. The usage and its connection to the early outcomes, though, are fascinating. Not fascinating enough for an adjustment, mind you. Once the weather warms, fastball-splitter becomes a more dangerous combination in the upper parts of the zone. Whether the new pitch mix is permanent, whether the slider gets more involved again, and whether we Estrada go back to working the edges and outside of the zone more frequently — these will all be important considerations as the season progresses.

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