Hitter Statcast xHR Underperformers — May 10, 2021, A Review

As I wind down my in-season metric reviews, I now move along to Statcast’s xHR calculation. In early May, I shared a list of hitters whose xHR total was at least one home run more than their actual totals. I wasn’t entirely sure what the best way to review how this group performed over the rest of the season, so I settled on HR/FB rate through May 8 versus the rest of the season. I ruled out AB/HR because strikeout and fly ball rates influence that rate and a homer can only be hit if the ball is put into play and isn’t on the ground.

Overall, this was a pretty good outcome, as 11 of the 14 hitters did increase their HR/FB rates over the rest of the season. Three of them increased it by double digits, but two of those three started from 0%. The three that suffered HR/FB rate declines over the rest of the season all started out with marks of at least 20% already, so skills regression proved a more powerful force than luck regression for them.

Trevor Story was our biggest xHR underperformer, and it wasn’t even close. Coors Field is a fascinating park and it was why I chose to get rid of the park factor component of my xHR/FB rate equation. Most park factors are driven by park dimensions and weather. On the other hand, Coors’ thin air actually increases distance, so if you’re calculating a xHR or xHR/FB rate and distance is one of your inputs, then applying a home run boosting park factor to Coors batters would be double counting. This may be part of the issue with Statcast’s Rockies xHR calculations, but their calculation is a black box, so I have no idea.

All that being said, I’m guessing Story’s xHR calculation was inflated to begin with, but even if adjusted, would have resulted in him underperforming. His early season HR/FB rate would have been a career low. He rebounded some the rest of the way and pushed it above his 2020 mark, which now remains as his career low. I wonder what has happened to Story as the HR/FB rate decline began last year and didn’t rebound this year. He’ll be another fun one to follow if he signs elsewhere.

Wow, Statcast totally nailed Salvador Perez’s big rest of season. His early season HR/FB would have been just fine as the second highest mark of his career, or really the highest mark over a full season if he sustained it considering his 2020 mark came over just 150 ABs. Instead, he took it up a notch and finished with the highest HR/FB rate of his career. I don’t know where all this power suddenly came from, especially after he missed all of 2019 recovering from TJ surgery (remember, hitters injure their elbows and get that surgery as well). What I do know is that I can’t imagine he’ll go for a price reasonable enough for me to roster him as a catcher entering his age 32 season and coming off a career fantasy season.

After a brutal start with a shocking lack of power, Jorge Soler was undoubtedly dropped in many shallow leagues. Even his xHR total was likely a bit disappointing, so it wasn’t just a matter of bad luck, but his skills were clearly not at peak level in the early going. While he rebounded some with the Royals and finished his partial season with them at a 13.3% HR/FB rate, he really rook off after arriving in Atlanta. His HR/FB with the Braves jumped to 21.9%, which was much more in line with preseason expectations. Most encouraging here is the career best strikeout rate. There’s a lot to like here heading into 2022.

Ya know, in my local shallow mixed league, I made an offer for Charlie Blackmon when I needed an outfielder under the assumption he would rebound and look closer to the player he was from 2016-2019, rather than 2020. It’s a good thing my offer was rejected because he wouldn’t have done a whole lot better than a free agent outfielder. With the steals looking gone and a career low batting average, he has gone from elite outfielder contributing in potentially all categories to replacement level. At age 35, does the power rebound at least? He’ll certainly come cheap enough to be worth finding out.

J.T. Realmuto’s HR/FB rate fell the most over the worst rest of season, but that merely knocked down his mark to his 2018 and 2019 levels, suggesting it was his small sample 2020 that was the fluke. At least he gave his owners a career high 13 steals, so he likely at least broke even despite hitting fewer than 20 homers.

Daulton Varsho is going to be a super popular “sleeper pick that isn’t” as a catcher eligible hitter who may play full-time somewhere else. His attractiveness on draft day is going to heavily depend on your league, as in some he might be able to sneak through cheaply, while in others, a bidding war will ensue on everyone’s favorite target and he goes so expensively, he now needs to break out just to break even.

It was a nice rebound season for Paul Goldschmidt after his disappointing 2020 season, and perhaps his Statcast xHR convinced you to acquire him early on if you were in need of a corner guy. While his HR/FB rate didn’t rebound all the way, he offset it by sustaining most of his strikeout rate improvement from 2020 to post the lowest strikeout rate of his career over a full season. Pretty impressive for a 33-year-old. Not only that, but suddenly his steals returned, as he swiped double digit bags for the first time since 2017. I can’t imagine betting on that happening again.