Last 30 Day SIERA Regressors

Last Thursday, I identified and discussed nine starting pitchers that had improved their SIERA marks the most over the last 30 days. Today, let’s check in on the starter who have seen their SIERA marks spike over the last 30 days. Sell while you can or hold on for the return to early season form?

Luis Castillo is enjoying that full season breakout year we expected last year, right? Not so fast. Though his ERA remained elite, he actually held a near 4.00 SIERA through May 30. That’s because of his double digit walk rate, though the big strikeout rate was nice. Over the last 30 days, his SIERA has ballooned to a disgusting 5.13, as his already high walk rate has surged to an impossibly high level in his last five starts. If you prefer more underlying skills than results (I do!), then there’s this — his strike rate earlier in the season sat at 59.7%, which was already well below the league average and his previous seasons, but has declined to just 57.4% in his last five starts. Elbow injuries typically correlate with a loss of control. So while I hate to speculate on injury, it wouldn’t surprise me in the least if we learn soon that Castillo’s arm isn’t quite right and he lands on the IL.

I hope no one picked up Andrew Cashner even during his short acceptable pitching streak. He’s bad.

I’ve never been a fan of Jose Quintana and the recent drop in strikeout rate means he’s at best just a streamer in shallower mixed leagues. Even then, I’d be hesitant to pick him up.

Yesterday, Jake Arrieta improved upon those scary last 30 day strikeout and walk rate, but man were those really terrible marks. He had walked almost as many as he struck out! I doubt any of you are holding Arrieta in the hopes his pre-2018 form returns, so this is just a final reminder that that version is not coming back.

LOL, Gerrit Cole appears here solely because his SIERA jumped from elite to merely very good. Obviously, he was never going to maintain a 39% strikeout rate. I wonder if he ever would have become this good if he remained on the Pirates. If you say no, then man do you need to give loads of credit to the Astros for turning him into a superstar ace.

Sheesh, what happened to Stephen Strasburg’s strikeout rate?! His velocity is another step down this year, which means he’s now just a garden variety right-handed starter. That’s a big fall from when he used to be one of the top flamethrowers in the game. His velocity hasn’t fallen further over the last 30 days though, but two of his four single digit SwStk% games have come in the last 30 days. I don’t think there’s anything to worry about now that you weren’t worrying about before these last 30 days.

I hope no one owned Eric Lauer, as his SIERA was already bad and went to unplayable, even in NL West only leagues.

I still can’t believe the first half Mike Minor has enjoyed. Unfortunately, he’s doing it with lots of smoke and mirrors. His LOB% ranks second highest in baseball right now, and unlike some others who typically post inflated LOB% marks, his sits at just about 75% for his career, which is only marginally above average. His SIERA is almost identical to last year, but his ERA is nearly 1.80 runs lower. Then you throw in a much weaker last 30 days, and something’s gotta give. A prime sell candidate.

Julio Teheran has been a consistent SIERA-beater (though not sure why), as he has outperformed in every season of his career. But this is crazy, even for him. His season SIERA is 5.24, which is terrible enough, but his last 30 day SIERA is near 6.00, as the strikeouts have disappeared! Every time you start him, you’re playing with fire, making you a bigger risk-taker than I! Give me a strong middle reliever instead.

Zack Greinke’s skills keep declining, but his ERA has yet to feel the impact. His average fastball velocity is now just below 90 mph for the first time in his career, while his SwStk% has dropped into single digits for the first time since 2012. An elite walk rate sitting at a career low mark has helped, but that’s hard to bet on being maintained. I know how hard it might be to try selling high here, but the numbers are screaming major regression.