Potential Starting Pitcher HR Rate Regressors — May 27, 2021

Yesterday, I used the Statcast Home Runs Leaderboard to identify and discuss the starting pitchers who have allowed more home runs than expected according to Statcast’s calculation. Today, let’s flip to the starting pitchers who have allowed fewer home runs than expected. Are they any sell highs among this group? Let’s find out.

On first glance, you wouldn’t think there was anything fluky about Michael Wacha’s home run rate, as his 12.1% HR/FB rate is just below his career 12.4% mark. But if you scroll down on his player page, you might notice the absurd 13.6% Barrel%, which is likely driving that much higher xHR total. Wacha has allowed extremely hard contact this season, but his BABIP is actually right around league average, while his HR/FB is below. So one of two things are likely to occur over the rest of the season — either he reigns in that hard contact and it starts to support his current BABIP and HR/FB rate or both marks are headed for jumps and any hopes of hitting that 4.09 SIERA disappear. Since it’s only been 30.1 innings, I’d lean more toward the hard contact rate coming down, which must happen to earn any sort of positive value in deep mixed and AL-Only leagues.

Man, Brad Keller’s HR/FB rate already sits at 16.7% and Statcast thinks it should be even higher! Keller has added velocity this year, but that hasn’t increased his SwStk% or strikeout rate enough to matter. And obviously, if you check out his Barrel%, you’ll see why he is allowing a high rate of home runs relative to the fly balls he has allowed. Unless and until he could translate that extra velocity into a strikeout rate over 20%, he’s just not an appealing fantasy option. Last year’s fortunate 2.47 ERA (4.82 SIERA) jacked up his perceived value far higher than deserved.

It’s hard to earn positive fantasy value as a Rockies starting pitcher, but Germán Márquez has tried his hardest and has succeeded in the past. But BABIP and home run issues will always be there, which is why he’ll always underperform his SIERA. Interestingly, his SwStk% has remained super consistent between 12% and 13% every season since 2018, but his strikeout rate has jumped around from a low of 21.2% to a high of 28.2%. That’s a huge range given the consistent ability to generate whiffs.

Wow, Daniel Lynch already got demoted after posting an impossible 15.75 ERA over 8.0 innings, and yet Statcast thinks it could have been even worse thanks to additional expected home runs! I didn’t understand the excitement over him to begin with as he only posted a 23.5% strikeout rate at High-A, so his struggles were no surprise.

You wouldn’t necessarily know it just from his ERA alone, but Madison Bumgarner is having himself quite the rebound season. His SIERA sits at its lowest mark since 2016 and his strikeout rate the highest since that year. Bumgarner was able to limit homers on fly balls when he called AT&T Park home given its pitcher friendly effects, but Arizona isn’t quite as friendly. Still, even with an extra homer here and there, he’s performing better than many expected.

Once again, Mike Minor is getting bitten by either an inability to strand his own baserunners or bad luck from the relievers allowing his runners to score. It’s hard to figure out what’s causing the discrepancy between actual home runs and expected, as his Statcast metrics are generally in line with his previous seasons, while his HR/FB rate is actually already at its second highest mark of his career. With a SIERA well below his ERA, I still learn toward better results the rest of the way.

Amazingly, this is already the most innings in a season Matt Shoemaker has thrown since 2017! Statcast actually things Shoemaker’s home run issues should be even worse than they already are considering he’s already sitting with an inflated 17.9% HR/FB rate. As I questioned yesterday, once again we see a low BABIP/high HR/FB rate, and it’s just so weird. The biggest question here is what has happened to his strikeout rate, which had remained above 20% every season of his career, but has tumbled to just 13.7% this year. I would imagine he’s not being started in any leagues right now.

Nathan Eovaldi finally allowed his first homer of the season during his last start, which now gives him a tiny 2.1% HR/FB rate. He’s probably the only name on this list that isn’t surprising to find. Of course Eovaldi has lucked out to only have allowed one homer so far. But his SIERA suggests that even when his home run rate normalizes, his ERA still might improve, and his LOB% is bound to rise.