Starting Pitcher SIERA Overperformers — May 6, 2021, A Review

Yesterday, I reviewed the early season starting pitcher SIERA underperformers and discovered that the majority did indeed improve their ERA marks over the rest of the season, some significantly so. Now let’s flip over to the list of SIERA overperformers. Were these pitchers able to sustain their magic or did the force of regression prove too powerful?

Wow, talk about regression! All 10 starting pitchers posted a worse ERA over the rest of the season and nine of the ten posted a mark at least 1.17 runs worse than they had through May 4. Three of them ended up posting an ERA well above 4.00 over the rest of the way, including one with a mark over 5.00. These pitchers went from early shallow league surprises to tossed back into the free agent pool.

J.A. Happ, the biggest SIERA overperformer through May 4, ended up posting the highest rest of season ERA on this list. All of Happ’s “luck” metrics regressed back toward league average, after he posted an absurd .171 BABIP, among other unsustainable metric levels, early on. He then posted a .314 BABIP the rest of the way and disappeared from the fantasy radar.

Danny Duffy posted the lowest early ERA on the list with a mark well below 1.00, driven by good fortune in all luck metrics, of course, but primarily by stranding a crazy 95.4% of baserunners. That LOB% remained extremely high through the rest of the season at 83.8%. Unfortunately, he was limited to just 61 innings due to injury, so his ERA didn’t have enough time to fully regress toward his SIERA.

Speaking of injury, Matthew Boyd is another who ultimately succumbed to one and was limited to just 78.2 innings after his ERA jumped due to a reversion of his BABIP and HR/FB rate closer to the league average. His future is now up in the air.

John Means stranded every single baserunner (yes, a LOB% of 100%) early on, which obviously no one could sustain. He tried though, still posting a well above average 80.5% mark the rest of the way. In addition, the extreme fly ball pitcher continued suppressing hits on balls in play, but couldn’t maintain a sub-.200 mark he posted early on. Given his unique skill set that relies on hit suppression and stranding a high rate of baserunners, rather than striking out opposing batters, he’ll never end up on my fantasy teams as the risk is higher that he loses those skills or bad fortune finally rears its head.

Taijuan Walker was one of three that posted an ERA well above 4.00 the rest of the way, mostly driven by a tripling of his HR/FB rate and a decline in LOB%. His already low early BABIP actually dropped even lower the rest of the way, so he’s lucky more balls in play didn’t fall for hits or his ERA may have approached 5.00.

Kyle Gibson remained strong nearly the entire time he remained with the Rangers, but disaster finally struck after his move to the Phillies. The funny thing is his SIERA actually improved with the Phillies, but all his luck metrics moved in the wrong direction. I’ve always been surprised that Gibson hasn’t struck out more batters, as his slider has been elite at generating whiffs throughout his career, while his changeup and curveball have both generated a mid-teen SwStk%. If only his fastball/sinker was better.

Kevin Gausman was the only pitcher on the list that posted a rest of season ERA less than 1.00 run higher than his early season mark. He therefore managed to post a sub-3.00 ERA the rest of the way, even though both his BABIP and LOB% regressed dramatically. Now having signed with the Blue Jays, I think it could be difficult for him to earn his draft day cost, but that obviously will depend on what that cost is, which will vary by league.

I drafted Anthony DeSclafani in my local shallow mixed league and was thrilled with his early performance. I kept trying to trade him away given his significant SIERA outperformance, but no one bit and I held my breath every time I started him hoping his performance crash wouldn’t begin. Luckily for me, it has been delayed until 2022. Like Gausman, DeSclafani benefits from his home park and his defense, as the Giants staff posted the fifth lowest BABIP in baseball, despite a thoroughly mediocre UZR/150.

I’m always a fan of a historically AL pitcher coming to the NL for his first full season, so I was optimistic about Marcus Stroman, even though he did spend a small portion of the 2019 season with the Mets. He actually posted the lowest early SIERA on this list, so even if his luck regressed, he still figured to be a solid fantasy contributor. Both his BABIP and HR/FB rate increased, the latter of which actually doubled over the rest of the season. He ended up posting a career best strikeout rate, which is what was hoped for in his first full season in the NL. Still, he massively outperformed his SIERA on the season, so he might be overvalued next year, especially without a high strikeout rate cushion.

Finally, some may have though this was finally the Nick Pivetta we’ve all been waiting for in his first full season on his new Red Sox team. But, the skills didn’t agree, and with his HR/FB rate more than tripling to a league average rate over the rest of the season, his ERA shot back above 4.00, in line with preseason expectations after all.