Though it’s not yet set in stone, Clayton Kershaw is probably going to win the ERA title, and he’s probably going to win the National League Cy Young Award, because Cy Young Awards frequently go to the guys with the ERA titles. Yet Kershaw isn’t the only starter with an ERA under 2, after you lower the minimums a little bit. There are actually three of them, one of whom is Kershaw, who is demonstrably and understandably amazing. One of them is Jarred Cosart, whose ERA is a hell of a lot more promising than the rest of his numbers. And the third is Clay Buchholz. Kershaw stands out because his adjusted ERA is nearly half the league average. Buchholz stands out because his adjusted ERA is two-thirds Kershaw’s. And Buchholz, now, is back from injury.
Any ERA that low, for a starter, is unsustainable, especially for a starter in the American League and Fenway Park, but Buchholz’s xFIP- is way improved. His FIP- is way improved. Something that’s helped him prevent runs is that he hasn’t surrendered many dingers, as dingers count for runs automatically. But more interesting than that is Buchholz’s strikeout increase. Used to be that Buchholz’s strikeout rates didn’t quite match the quality of his stuff, or at least that was the perception. This year he’s taken a leap forward, striking out a quarter of the batters he’s faced. Changes in strikeout rate capture an analyst’s attention, and in Buchholz’s case, there’s something in particular that’s been driving this.
Now for the part where I give away the ending:
Bunts aside, there are two ways to get a strikeout: you can make a guy swing and miss, or you can throw a strike the batter doesn’t swing at. So, there are swinging strikeouts, and there are called strikeouts, and while it’s the swinging strikeouts we like to watch as indicators of dominance, all strikeouts count the same and there’s an art to leaving hitters frozen. In the image above, you can see Buchholz’s rates of swinging strikeouts and called strikeouts. His swinging strikeouts, this year, are more or less where they’ve been for a while. His called strikeouts are way, way up — to the point where they’re almost equaling his swinging strikeouts. The league average is that a quarter of strikeouts are called. This year, we find Buchholz around half.
This season, 232 pitchers have faced at least 250 batters. That’s an arbitrary cutoff, but look how willing you are to accept it. Buchholz ranks 164th in swinging-strikeout rate, between Alexi Ogando and Ronald Belisario. He ranks first in called-strikeout rate, well in front of Dale Thayer and Cliff Lee in second and third. Out of Buchholz’s plate appearances, 12.0% have ended with called strikeouts. The next-best mark is 10.5%. The highest mark last season was 11.0%. Buchholz’s own mark last season was 5.9%. That gets more into the chart above.
It’s not just what Buchholz is doing; it’s that he hadn’t done it before. Around baseball, there are 165 pitchers who have faced at least 250 batters in each of the last two seasons. Buchholz’s called-strikeout rate has increased by 6.2 percentage points, which is far and away the biggest increase in the majors. Chris Sale is the only other pitcher with an increase above 4 percentage points. Buchholz, suddenly, is generating a bunch of called third strikes, and as a result he’s looking more like the pitcher he was always supposed to turn into.
Digging into the platoon splits, we see increases against both righties and lefties:
Lefties are at 10%, where before they’ve hovered around 6%. Righties, though, are way up near 15%. This season, Buchholz has struck out 24 righties looking. That’s a career-high, despite all the missed time. Compared to last year, Buchholz has two more called strikeouts against righties, in four-ninths the sample. Of Buchholz’s 39 strikeouts of righties so far, just 15 have involved a swing at strike three. This feels like something truly extraordinary.
To try to get some sense of Buchholz’s strategy, we can plot his called strikeouts against the league’s called strikeouts:
Against righties, Buchholz has gotten his called strikeouts over the outer half, or near the outer edge. Against lefties, he’s alternated inner and outer edges. Know that the strike-zone boxes are included just as reference points, and they’re hastily-produced approximations.
All of his called strikeouts against lefties have come on fastballs, sinkers, or cutters — or, some variation of heat. Most of the inside ones have been sinkers tailing back over the inner edge. Most of the outside ones have been cut, with Buchholz targeting the back door. A sample, featuring James Loney:
His three most inside called strikeouts against righties have come on curves. For much of the rest, we find those back-door sinkers, with Buchholz taking full advantage of his horizontal movement. A sample, featuring Jayson Nix:
If you take a look at Z-Swing%, Buchholz, rather unsurprisingly, is in the group with the lowest rates. Batters have taken a lot of strikes, and not just in two-strike counts. More interestingly, from last year, Buchholz’s O-Swing% is unchanged. His Z-Swing% is down from 63% to 57%. So batters have swung less often, but only at pitches in the zone, which is an encouraging thing to see for a pitcher. Something else that most certainly helps: Buchholz has been given a more friendly zone this season. One in eight pitches out of the zone have been called strikes, against a league average of one in 14. Implied is that Buchholz has pitched to good receivers, and implied also is that Buchholz has done well pitching to spots right near edges. That’s where called strikes are found, and that’s where called strikeouts are found.
Looking back, Buchholz has generated a remarkable amount of called strikeouts. The big question, then, is what to make of this for the future. Swinging strikeouts tend to be more stable year-to-year, and those are taken to be a better indicator of pitcher ability. Called-strikeout rates bounce around. Since coming off the DL, Buchholz has generated just two called strikeouts over two starts. He didn’t get any on Sunday. But called strikeouts still aren’t random, and the correlation isn’t that much weaker than the one for whiffs, so it’s worth considering that Buchholz might have a new skill, now. He might have figured out a way to boost his strikeouts while leaving his contact rates virtually unchanged. It feels like there would be more reliable ways for a pitcher to get better, but if you think I actually really understand pitching, man, thanks, I appreciate it, but, nope. If Buchholz is developing mastery of the edges, then he’s got his job figured out.
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