Starting Pitcher SwStk% Surgers — June 6, 2022

Give me only one metric to evaluate a pitcher that isn’t an ERA estimator like SIERA and I’ll choose SwStk%. The ultimate validation of a pitcher’s stuff is his ability to make batters swing and miss. So let’s review the starting pitchers whose SwStk% marks have increased the most versus last year.

It’s been a love/hate relationship for me and Tyler Anderson. At the beginning of his career in Colorado, I didn’t touch him because of his home field, but believed his skill set could make it a mixed league asset if he joined another team. Sure enough, in 2020, he went to the best pitcher’s park in baseball as he joined the Giants, but injuries limited him to just 54 innings and his strikeout rate plummeted. Since then, getting out of Coors hasn’t done anything for his ERA and his SIERA has actually risen. So I had given up, which means that naturally this is finally the year, at age 32, that he is enjoying a breakout.

While his SwStk% has remained in double digits his entire career, it had never exceeded 12% until this year, which has resulted in a career best strikeout rate. Surprisingly, it’s difficult to figure out what’s driving the performance surge. His fastball velocity has been pretty stable the last three years, which is down from his 2016-2019 days, and is down a couple of ticks this year. The only real difference in his pitch mix is more changeups and fewer four-seamers. Is that enough to explain such a jump in SwStk%? The answer is that his changeup has been incredible this year at generating whiffs. It has generated an elite 26.7%, which I would imagine would be near or at the top of the changeup SwStk% leaderboard if there was one. I have no idea why his changeup has been so insane this year, but without improved fastball velocity or any other differences, it’s hard to believe he could maintain this level.

Pitching in the NL for a full season for the first time, this would have been a boon for Kyle Gibson in past years. But with the DH in both leagues now, it doesn’t matter. Still, his strikeout rate has increased to the second highest rate of his career, on the backs of the second highest SwStk% of his career. You don’t normally expect a 34-year-old to enjoy spikes in any of those metrics to begin with. Throw in the fact that Gibson’s sinker velocity (his most used fastball) is actually tied for the lowest of his career), and it’s pretty shocking to see that SwStk% surge.

He has thrown his cutter and slider more often, at the expense of his four-seamer, changeup, and curveball. The cutter has been a below average whiff pitch, but his slider remains elite, which leads to even better results since he has been throwing it more. Like Anderson, I remain skeptical this whiff rate is sustainable, especially given his fastball velocity decline.

Pablo Lopez is essentially been the same pitcher as last year (which is a good one), but lady luck has blessed him this year to the tune of a .246 BABIP and 84.5% LOB%. That said, his SwStk% has jumped to a career best, though his strikeout rate is actually down some compared to last year. Like the previous two names, Lopez has also lost velocity this year, and has thrown four-seamer and changeups, at the expense of his sinker and curveball. His four-seam SwStk% is down, which makes sense given its velocity decline, so it’s odd that he has thrown the pitch a bit more often. However, his changeup is clearly his best pitch, with by far the highest SwStk% of all his pitches, so it’s a positive that he is throwing it more without losing any whiff ability.

Incredibly, his sinker has generated a 15.7% SwStk%, which can’t possibly be sustainable, but it’s a pretty small sample, so hasn’t fueled his overall SwStk% by a whole lot. Once again, given the fastball velocity decline, I’m hesitant to believe his high changeup SwStk% is sustainable. But if he continues to throw it often, he could sustain a higher SwStk% just by virtue of throwing his highest whiff pitch more frequently.

Shane McClanahan has wiggled his way into several recent posts of mine, as his incredible breakout season continues. Unlike the others, there are some really changes to his pitches and mix. First, his fastball velocity has actually increased a touch, by 0.6 MPH. Second, he has thrown his changeup and curveball more frequently, at the expense of his slider. On its own, it’s an interesting switch, but until I dive into the individual pitch splits, there’s no way to know if it makes sense.

So when looking at his pitch splits, the first reaction is of awe, as two of his pitches have generated low-to-mid teen SwStk% marks, while the other two are up above 20%. That’s quite the deep repertoire! However, the odd thing is that his slider, which generated the highest SwStk% of his pitches last year, has done so again, so it’s curious why he has reduced his usage of the pitch so dramatically. Obviously, there’s no sense in quibbling, because whatever he’s done has obviously worked. Since he has also added grounders, he now has a legitimate claim to best pitcher in baseball. Seriously.

Ready to be impressed again? Including this year’s jump, Kevin Gausman has now increased his SwStk% for six straight years. Velocity isn’t at play here as he has been pretty stable, with a small decline, since enjoying a spike in 2020. His pitch mix has changed slightly, as he has increased usage of his slider, at the expense of his other three pitches. The big driver here is just better whiffiness from his non-fastballs. His splitter, which has always been one of the best pitches in baseball, is up to an absurd 28.5% SwStk%, which is a career best, while his slider is above 20% for the first time. Finally, his changeup is at the second highest mark of his career. So he’s featuring three insanely whifftastic pitches, to go alone with a 94.6 MPH fastball that gets as high as 98 MPH. As usual, it’s hard to best on these pitches remaining this good all season long, but he’s now been at this strikeout rate level or above since 2020, so it’s legit.