2021 Forecast — Potential HR/FB Rate Decliners

Yesterday, I used my xHR/FB rate equation to identify and discuss the hitters whose actual HR/FB rates most underperformed. Today, let’s flip to the other end of the spectrum — those hitters whose actual HR/FB rates significantly exceeded their xHR/FB rates.

Your eyes aren’t playing tricks on you. Yandy Diaz’s xHR/FB was actually negative. That’s because he failed to barrel or pull any of his fly balls, and the average distance of his flies and liners was right near the bottom. It’s a surprise because his 2019 HR/FB rate breakout was fully supported by his Statcast metrics. Aside from losing home run power when diving under the surface, his FB% collapsed after surging in 2019. Obviously, his HR/FB rate doesn’t matter all that much if he rarely even hits a fly ball. It’s anyone’s guess what he’ll do in 2021, but at least he’s got the foundation of some strong skills, but currently those are more beneficial in real baseball than in fantasy.

DJ LeMahieu was the poster boy I used when describing some of the flaws of my new xHR/FB rate equation, and really, any of this type equation that isn’t accounting for the exact location of his fly balls and line drives at the stadium he was hitting in at the time. Likely in any other stadium, LeMahieu would be plopping along with a HR/FB rate around 10%. But not in Yankee Stadium. While his Statcast metrics supported his 2019 HR/FB rate surge, his Barrel FB% came crashing down in 2020, as did his average distance. That said, his Oppo FB% skyrocketed, which is typically a bad thing. But not when you’re a right-handed hitter in Yankee Stadium trying to take advantage of the short distance down the right field line.

Since becoming a Yankee, he has posted a 30.7% HR/FB rate at home, versus just a 10.7% mark away. He has also hit his fly balls to the opposite field 54.5% of the time at Yankee Stadium, versus just 35.8% in away parks. Think he has adjusted his hitting approach to take full advantage of his home park? He sure has! So while odds are he does suffer a decline in HR/FB rate in 2021, and perhaps a significant dropoff, I don’t think there’s much of a chance it slides all the way down to his xHR/FB rate, or anywhere close.

Luke Voit is the second straight Yankee on here, but unlike LeMahieu, he has not benefited greatly from his home park. Voit’s home/away HR/FB rates are quite similar, and he was almost exactly on par with his xHR/FB rate in 2019. His 2020 mark looks mostly like good luck, though a glance at his Statcast metrics suggests that the mix-up between flies and line drives could potentially be the culprit here, as every other metric moved strongly in the right direction versus 2019. Still, it’s hard to bet on another 30%+ HR/FB rate, but perhaps he’s not due for a fall back to the low 20% range either.

I thought the days of the Mets signing players coming off career seasons was over? It was just 111 plate appearances, so it’s silly to call James McCann’s performance a career season, but did he benefit from quite a bit of good fortune, from his HR/FB rate to his BABIP. What’s crazy is that McCann has underperformed his xHR/FB rate slightly every single year of the Statcast era, making his 2020 outperformance stand out even more.

Instead of focusing on how fortunate Nelson Cruz may have been to post a ludicrous 41% HR/FB rate, let’s instead focus on the fact that Cruz still managed to post a 31.6% xHR/FB rate (highest of his career during the Statcast era) at the tender age of 40. What’s amazing is that his career really didn’t start until age 28.

Like Cruz, let’s focus on Jesse Winker’s 31.6% xHR/FB rate, as Winker wasn’t supposed to be a big power hitter when ranked as a top prospect. In fact, the latest scouting report posted on his page shows Game Power of just 30/40 and Raw Power of just 40/40! He has clearly transformed himself and since he also walks a ton, has been a strong offensive performer. This is also the second straight season Winker has massively outperformed his xHR/FB rate. The sample sizes of each of his seasons has been small, but we know Great American Ballpark is a home run friendly environment, so it’s certainly likely that some of the gap, though unlikely all of it, can be explained by that park.

Yikes, so not only did Christian Yelich’s strikeout rate skyrocket last season, but his HR/FB rate outperformed his xHR/FB by the largest amount in his Statcast era career. He outperformed in 2019 too, but by a lesser degree and had underperformed consistently while with the Marlins. It seems clear that if he underperformed each season with the Marlins and has outperformed each season with the Brewers, his home park certainly has something to do with it, and Miller Park is friendly for left-handed homers. But as usual, I can’t blindly chalk up the entire gap to his home park, so he might have to regain some of his lost skills to post a HR/FB rate over 30% for a fourth straight season.

I chose to end this list with rookie Ke’Bryan Hayes, because he so massively outperformed power expectations during his cup of coffee that he deserved a short discussion. Hayes had never posted a HR/FB above 8.6% in the minors, or an ISO above .151. His prospect status was more due to his defense than his offense, though his offense figured to be decent enough with upside. It’s likely that his surprising power is deceiving fantasy owners into inflating 2021 expectations, which could lead to disappointment. Remember, this power outburst came over just 85 at-bats, which is the smallest of sample sizes! While he has some speed too and could be the rare corner guy that contributes both some homers and steals, don’t go thinking you’re buying a potential 30 homer guy.