Last year, we looked at different pitch types and when their CSW% (called strikes plus whiffs) became predictive of future performance on those pitches. Fastballs take the longest (200 pitches thrown) while we get a pretty good idea of how many strikes a curveball will get after just 30 thrown.
One hypothesis is that because starters typically have more pitches to mix into their repertoire, it introduces another variable that makes any one pitch more difficult to stabilize. The fastball playing off three other pitches, for instance, may lead itself to more “noise” in the sample with hitters being fooled more often looking for other pitches. Relievers, on the other hand, are more likely to just have one or two pitches they’re throwing the majority of the time, so a pitch’s “true” ability to generate whiffs or called strikes may stabilize more quickly.
It’s also important to note that “stabilization” doesn’t mean that a pitch’s CSW% at this point of the year is locked in– only that it is starting to tell us something about how hitters are reacting (or not) to the pitch. With those caveats in mind, here are the most-improved pitches in CSW% so far in 2022, with the above threshold minimums being reached.
Four-Seam Fastball: Lucas Giolito, White Sox
It’s hard to say Lucas Giolito’s 2021 was disappointing while covering a career high in innings, a mid-threes ERA and still striking out better than a batter per inning. It perhaps didn’t match the lofty expectations placed on it, however, as Giolito’s FIP and ERA were higher than any season since 2018 and his strikeout rate lower.
2022 has been a different story, with a career-high in strikeout rate and an ERA below 3, even while allowing a career-high .333 BABIP. One of the first differences at which to point would be Giolito’s four-seam fastball improvement. Last year, Giolito managed whiffs or called strikes on 29% of his four seamers, but so far this year has reached an incredible 39% CSW, while throwing the pitch about 5% more often than he did in 2021.
Surely, with those kind of results, he’s had an uptick in velocity, right?
Oh. Hm. It must be moving around a lot more, fooling batters into swinging and missing 27% of the time?
Ah, well. Nevertheless.
So how has Giolito increased his CSW% on his four-seamer more than any other pitcher in baseball? The chart of his pitch movement above may offer a clue. Giolito has more than doubled his curveball usage this season. His curve was below average last season, but now has above average movement, even though the results have been somewhat pedestrian on that particular pitch. Instead, it seems to be a case where the four-seamer and curve are playing off of each other and the whole repertoire being greater than the sum of its parts.
To see how this is working, we turn to our old friend spin mirroring. When two pitch types have exactly opposite spin, it is harder for hitters to pick up. It does seem that Giolito’s four-seamer and curve have been playing off of each other, making each pitch slightly harder to discern or square up:
2021
2022
Giolito’s four-seamer and curve are more directly opposed in their spin direction in 2022, perhaps allowing the four-seamer to play off of it and make hitters late on the pitch. This seems to be an instance of instead of the pitch itself getting better, the overall repertoire is better and working together. It’s led to results in Giolito’s outcomes, but the four-seamer itself has been more effective, as it’s led to a run value of -5 already, after sitting at 0 last year.
Slider: Chase De Jong, Pirates
De Jong has struggled to catch on and stick in his career thus far, now pitching for his sixth organization at just 28 years old. Mainly a starter in his stops in the minors and majors, Pittsburgh now has him in the bullpen full-time, where at least his slider has benefitted.
What’s interesting about that slider is that each of the past three seasons, De Jong has been able to increase the amount of movement he’s getting on it. This year he’s throwing the slider around two ticks slower than last year, but with approximately the same amount of spin. It’s led to getting more vertical and horizontal movement on the pitch, and a whopping 14.5% increased CSW% along with it. De Jong has probably found his success with it too, as he’s throwing the slider 30% of the time, up from 23% last year.
There’s something interesting here with De Jong. His ERA is 2.0 in the early going, albeit with a 4.57 xERA owing to a sub-.200 BABIP and stranding 85% of baserunners. It’s notable that he’s accomplished this with a pretty low strikeout rate so far across his 18 innings pitched so far (13.9%). But, De Jong has demonstrated strikeout stuff in the past, most recently with Houston (23.7%) and even last year in Pittsburgh (19.9%). And while he’s in his late-20s pitching in AAA, the past couple of years in Indianapolis he was striking out better than a third of the batters he faced. There still may be some strikeout upside here for De Jong, especially as he continues to refine and improve that slider.
Heasley’s changeup barely qualifies for the leaderboard here, as he’s thrown it just 52 times all season in 8 innings pitched. That said, Heasley certainly seems to have some confidence in it, as he only threw it 54 times across 14 innings in 2021. The changeup has gone from a 9% CSW to 29% in that time span.
Similar to Giolito, Heasley is probably benefitting quite a bit from a pitch mix change that’s playing up the entire repertoire. The fastball is a good one, as Heasley has above average velocity, spin, and movement on it. He’s increased his usage of the changeup mostly at the expense of his curveball, which allowed a nearly .600 xSLG in 2021.
If the fastball continues to play up and remain Heasley’s best pitch, it may be the case that having a couple of off-speed pitches (the curve and change) gives hitters more chances to wait back on it. Simplifying into the four-seamer and changeup may be allowing the change to play up more because hitters are focused on the fastball.
The changeup just clears the bar for usefulness in predicting future results, but a 20% jump in CSW is still notable for the Royals’ pitching prospect. Hitters will continue to adjust, and with below-average drop on the changeup it’s unlikely Heasley has one of the best in the business, but it’s an encouraging development nonetheless.
Photo by Ken Murray/Icon Sportswire | Adapted by Drew Wheeler (@drewisokay on Twitter)