Starting Pitcher SwStk% Decliners — June 7, 2022

Yesterday, I discussed the five starting pitchers that have enjoyed the largest SwStk% surges versus last year. Let’s now discuss the decliners.

Shane Bieber’s SwStk% has declined to its lowest since his 2018 debut. That’s the negative. Looking at it differently though, a 13.8% SwStk% is still pretty darn good! It’s just not vintage Bieber good. As I’ve noted in previous posts, his fastball velocity is down to a career low, and it hasn’t exactly been trending up in recent outings, even though he averaged his third highest game velocity of the year during his last start. He hasn’t averaged more than 91.8 MPH in any starts this year, which is pretty crazy considering he averaged 92.9 MPH all of last year. I’m actually surprised his SwStk% and strikeout rate have remained as high as they are, but it’s just a testament to how good his slider and curveball are.

For years, German Marquez had been the rare Rockies starter that was worth rostering. But this season, his SwStk% has fallen off a cliff, dropping into single digits for the first time since 2017, and bringing his strikeout rate down to its lowest mark since his 2016 debut over a tiny sample. Unlike Bieber, his fastball velocity is actually fine, and up a tick from last year. He has swapped out four-seamers and curves for sinkers and sliders, which given the average SwStk% of each, would typically result in a slightly higher overall SwStk%. But his four-seamer has been awful to generating whiffs this year, as its SwStk% sits at a career low, while his curve’s SwStk% is also at a career low. So it actually makes sense that he made the change in pitch mix, but the his sinker was never any good at inducing whiffs, so that hasn’t helped any. The increased slider usage is a positive, but just not enough to offset the declines elsewhere. I don’t know what the issue is, but I’m not going to target a pitcher on the Rockies, no matter how many decent seasons they have had in the past.

Cal Quantrill’s magician act continues. His SwStk% was already low last year, and is now among the league laggards. His strikeout rate, which was also below average, has fallen even further. And yet thanks to another suppressed BABIP and microscopic HR/FB rate, his ERA is about one and a half runs below his SIERA. That’s actually a slightly smaller gap than last year! Combine the ERA regression risk with a weak strikeout rate, and he makes for one of the worst pitchers to fill your starting roster with. Oh, plus his fastball and sinker velocity have both sunk by a mile and a half. Keeping him active is the definition of pushing your luck! However, I’m open to hearing arguments for him possessing the skills of a low BABIP and HR/FB rate pitcher. In my mind, the sample size remains far too small to make any sort of declaration, which means regression toward underlying skills is still the percentage play.

It’s looking more and more clear that Zach Plesac’s breakout 55.1 innings in 2020 was the fluke, rather than a performance level we might expect him to rebound to. Like some of the others on the list, his velocity is down a mile per hour, but his pitch mix hasn’t changed all that much. His changeup and curve are no longer double digit SwStk% pitches, so he’s left with just his slider as an above average pitch for whiffs. Likely due to the lost velocity, his four-seamer is further below average than it used to be. It’s hard to bank on much improvement from here.

Jameson Taillon’s SwStk% sits at its lowest since 2017, and his strikeout rate is at the second lowest mark of his career. But great fortune has resulted in a sub-3.00 ERA, masking the skills decline. He’s made some significant pitch mix changes, including reducing usage of his four-seamer and curve, in favor of a new cutter, plus more sinkers. The cutter has become his best whiff pitch, while his curve has lost some whiff ability. So it makes sense that he’s throwing the pitch less, but it hasn’t been enough to avoid an overall drop in SwStk%. He’s not going to maintain a 2.2% walk rate, so with a below average strikeout rate, and career bests in all the luck metrics (BABIP, HR/FB, LOB%), he’s a clear sell high candidate.

I was quite the fan of Josiah Gray as a cheap dart throw this season, but he’s lost some whiff ability and his control hasn’t rebounded. His velocity is down just a tick, but nothing to worry about, while he has reduced his four-seam usage in favor of his slider. That would typically be a good change for strikeouts, but he was coming off a really strong 2021. So this season, both his slider and curve have lost SwStk%, but still remain well above the league average. However, his four-seamer is a big blame, as it’s dropped to well below average, while his 30 changeups haven’t even generated one swinging strike. I have no idea why he bothers to even throw any. I think given his strong slider/curve foundation, and mid-90s fastball, I remain a supporter. However, at some point the control needs to return to his minor league days, and his extreme fly ball rate is scary (though it does reduce his BABIP).