Starting Pitcher SIERA Overperformers — May 6, 2021

Yesterday, I listed and discussed the qualified starting pitchers that have most underperformed their SIERA marks. It was a good initial list of potential acquisition targets (hopefully to be had at a discount!) in which to perform further research. Now let’s move to the SIERA overperformers. This is the group you should be thanking Lady Luck for if you own any of them as their ERAs are likely to rise, perhaps significantly, over the rest of the year. That doesn’t necessarily mean they will be bad and hurt your fantasy team, but you may very well get far more value in return for what they will provide over the rest of the way if you dangle them to your leaguemates in a trade.

The overperformer list is far larger than the underperformer list, so I had to cut it off somewhere. Make sure you’re always checking your pitcher’s SIERA, because it doesn’t mean they haven’t been lucky if they don’t appear on here.

J.A. Happ is far and away the leader in ERA-SIERA gap, and is the only starting pitcher outperforming by more than three runs. Not only is he significantly outperforming, but his SIERA suggests he’s actually been a bad pitcher. There are all kinds of red flags here for the 38-year-old, including fastball velocity that has dropped to its lowest mark since 2010, driving a collapse in strikeout rate to what would represent a career low. I’m guessing Happ doesn’t have a lot of trade value, but he did post a 3.47 ERA and a deep mixed or AL-Only league owner might think he’ll continue to be a solid pitcher, willing to give up an underperforming hitter. Remember that Happ has outperformed his SIERA for his career, but by only 0.27 runs, which is nowhere near his current 3.00+ gap.

Obviously Danny Duffy isn’t going to maintain a sub-1.00 ERA and you didn’t need SIERA to tell you that of course there’s been some luck involved in his results. The more important note here is that his SIERA is the lowest its best since 2016 and only the second time it’s below 4.00. His strikeout rate and SwStk% have both shot up to career bests as his fastball velocity has increased to its highest mark since 2016, before it tumbled down from there. If he maintains this velocity spike, I think he could post a sub-4.00 ERA the rest of the way. I’m not sure you’ll get enough value in return, even with his current sub-1.00 ERA, right now to be worth selling.

Entering 2020, Matthew Boyd was an obvious sleeper when he underperformed his SIERA and enjoyed a massive strikeout rate spike. Unfortunately, that spike was short-lived and failed to carry over to the shortened season, while his poor HR/FB rate ensure his ERA marched even higher. This year, his strikeout rate has plummeted, but now luck has been on his side! It would be easy for his owners to pat themselves on the back for buying him cheap on draft day, but this is not the Boyd his owners expected. His velocity is fine and pitch mix hasn’t changed much, but his slider’s SwStk% is nearly half his career mark, so that’s the driver of his strikeout rate decline. I have no idea what’s behind it, but given his current skills, his ERA is a complete illusion.

John Means’ strikeout rate has jumped again despite a small drop in fastball velocity and it’s backed by an increased SwStk%. So he’s legit a better pitcher, but check out that 100% LOB%! It’s not a true 100% LOB% because he has allowed some baserunners to score, but the runs scored on home runs assumption in the formula causes that mark to hit 100%. Obviously, that won’t continue and neither will his sub-.200 BABIP. So like others on the list, Means is likely to remain a pretty good pitcher the rest of the way, just not nearly this good. It’ll be up to you to determine whether the value you could get in return by trading him is higher than he’s expected to produce.

A return to the National League without the DH should have been promising for Taijuan Walker, but his skills haven’t improved at all. What’s crazy is he’s allowed a 33.3% LD% but only a .261 BABIP. That seems extremely hard to do. I think his walk rate will improve enough so his SIERA comes down, but without continued good fortune, I’m not so sure a sub-4.00 ERA the rest of the way is in the cards.

For years we were waiting for Kyle Gibson’s strikeout rate to spike. It finally did in 2018 and has remained in that range ever since. In 2019, his SwStk% surged, giving us hope that strikeout rate had another potential gear higher. It then dropped last year, but is back up again to a new high this year, but the strikeout rate is the same as always. So Gibson looks like the same pitcher, but his always inflated HR/FB rate and BABIP are now significantly better than league average. I wouldn’t bet on that continuing.

Kevin Gausman’s strikeout and walk rates have reverted right back to their 2019 levels, suggesting maybe last year’s strikeout rate surge was the outlier. But now his luck has reversed as the oft-inflated BABIP guy is now sitting pretty with a tiny .210 mark. Gausman should continue to be solid, but not like this.

I was a fan of Anthony DeSclafani in deeper leagues due to the park switch, but I didn’t expect him to be this good early on! The good news is he has fully rebounded from last year’s strikeout and walk rate disasters and now calls a pitcher friendly park home. He should maintain mixed league value all season, but ERA regression is obviously coming.

So much for the strikeout rate bump full-time in the NL without the DH for Marcus Stroman. Obviously, it’s only been 29.1 innings so that strikeout rate surge could still occur, but it hasn’t just yet. The good news is his SwStk% sits at a career best while he continues to generate tons of grounders. Lucky, yes, but I like him for continued value all season.

The long-awaited Nick Pivetta breakout is here! Errrrr, no, it is not. While a jump in strikeout rate is nice, it’s not supported by much change in SwStk% and his control has been downright terrible. He’ll start to allow home runs on his flies and his ERA will be above 4.00 in no time.