These daily questions posts are useful for throwing stuff out there without me having done enough work to reach a full conclusion that would justify an actual article of interest. This one is probably more substantial than most, though. Here goes.
Here are a few facts about Spencer Schwellenbach:
- He has been phenomenal to date (3.6 career fWAR in 192 innings);
- If not for some HR/FB stuff this year, he’d be even better (career 81 ERA-, 87 FIP-, 82 xFIP-); and
- As covered by Jared Greenspan, Schwellenbach is the rare guy to do it with an arsenal of six pitches, all of which get some play.
Here’s another fact about Schwellenbach: his times through the order splits look… normal-ish?
In case you don’t want to do the math yourself, the data from 2024-2025 basically match what we expect: starters are better than their overall numbers the first time through (1TTO), pretty much the same as their overall numbers the second time through (2TTO), and worse the third time through (3TTO). I am not surprised to see the FIP effects exceed the xFIP effects (though I wouldn’t be surprised to see no difference between them, either), under the premise that HR/FB isn’t meant to regress to league average when batters are annihilating pitches, but that’s not the primary point of what I’m talking about here.
How does Schwellenbach compare? For one, it’s important to note that he’s been way better than an average starter — nothing here is intended to indicate otherwise in any way. But, we can see that his 1TTO performance is way better than his baseline, even relative to the league, while his 3TTO performance is way worse than his baseline, even relative to the league — especially in terms of homers yielded.
Back in 2011, Carmen Ciardiello found (after revising his own prior analysis) that an arsenal with fewer pitches suggested steeper TTO penalties — this seems intuitive (not that intuitive things are always, or even often, correct in baseball, or in life) because the whole premise of the TTO penalty is based around “looks.” (The earliest TTO penalty work specifically identified that batters who saw more pitches earlier in the game did better against the same pitcher later in the game, than batters who saw fewer pitchers than their teammates; more recent work has found that the TTO penalty may be morphing into a batters faced penalty due to the proliferation of technology available to players in the dugout, which may substitute for their own personal “looks” at the pitcher.)
But, hold on a minute — Schwellenbach has six, count ‘em, six pitches. That’s not two. That’s more than two; that’s more than most pitchers have. So, what’s the deal? Here are my thoughts, albeit, as mentioned at the beginning, not fully formed. First, let’s look at how often Schwellenbach uses each pitch.
Against righties, Schwellenbach goes from a 2-in-3 chance of throwing a four-seamer or slider 1TTO, to basically a 1-in-2 chance by 3TTO, with cutters, curveballs, and splitters making up the difference.
Against lefties, Schwellenbach has to get craftier early, attacking them with four-seamers, curves, and splitters early. But then, you see kind of a complicated pattern — four-seamer usage declines, but there’s comparatively more curves and splitters 2TTO, but then fewer curves with cutters and sliders making up the difference 3TTO.
Let’s add another puzzle piece. I think we’re getting somewhere with this one.
Is Spencer Schwellenbach good? Absolutely, he’s pretty great. But, he’s great specifically because he dominates righties. Not only that, but his domination of righties has, at least so far, been largely immune from the times through the order penalty. Whatever he’s doing to mix it up against righties with his arsenal seems to be working. But…
… he kinda sucks against lefties. Okay, that’s not accurate at all, he’s still better against lefties than your bog-standard right-handed starter… at least until it gets to the third time through the order. Moreover, Schwellenbach’s HR/FB “issues” and overall “challenges” appear to be concentrated in facing lefties the second and third times through the order.
How to reconcile this with the pitch usage bars above? I’m not fully sure. I guess you could say he varies his arsenal more against righties than lefties, in part because he already has to start being somewhat crafty against lefties to begin with. We could also look at relative hitter success against each pitch — though this forces us to look at xwOBA, which is in turn potentially influenced by the identity of the batters he’s faced in each split so far in his relatively short career. But let’s do it anyway.
Against righties, the story is basically that Schwellenbach is a nightmare. Everything works, and while the slider in particular loses effectiveness over time, by 3TTO, the high variety of looks he continues to offer, all with some degree of inherent quality (apparently), is tough.
But against lefties, Schwellenbach seems more like just a guy, with a deadly splitter. Seriously, it’s all about the splitter. You can actually kind of see his 2TTO and 3TTO pitch usage against lefties engage in a dialogue with these xwOBA-against numbers — at least in the slider, where it seems to be surprising lefties late… except that yesterday, both Gavin Sheets and Jake Cronenworth hit 3TTO homers off Schwellenbach’s slider.
The thing is, I don’t have any kind of definite conclusion about Schwellenbach’s direct reason for struggling against lefties, or how a simple pitch mix tweak can fix it and make him the best starter ever. Fundamentally, though, he’s a guy whose really good pitching comes because he dominates righties and has figured out how to do so even when they see him multiple times a game, but the stuff against lefties is still a work in progress. I’d offer some words about hey, maybe the Braves should be more aware of this and manage game states to avoid him having to figure out how to get lefties out in close games after they’ve seen him once or twice, but at this point, we both know that’s not happening. So I guess I’ll just track this to see if he ever does figure out a way to get lefties out multiple times, and if so, how he’s evolved to do so.
Daily Notes
Record: 25-27
Yesterday’s wOBA and xwOBA: .265 / .253 (Season rank: 13th | 12th)
Yesterday’s wOBA and xwOBA allowed: .342 / .274 (Season rank: 15th | 12th)
Yesterday’s homers: 0
Yesterday’s homers allowed: 3
Record when out-xwOBAing: 16-11 (League: 574-208)
Record when out-xwOBAed: 9-16 (League: 208-574)
Record when out-wOBAing: 21-3 (League: 660-125)
Record when out-wOBAed: 4-24 (League: 125-660)
Record when outhomering: 11-5 (League: 410-121)
Record when outhomered: 5-14 (League: 121-410)
