2019 Review — xHR/FB Rate Negative Validations

Last week, I identified and discussed a slew of hitters whose xHR/FB rates validated their surprisingly strong HR/FB rates. Today, let’s look at some of the disappointing hitters in HR/FB rate that were validated by a dramatic decline in xHR/FB rate. Remember, an appearance here doesn’t mean these hitters should be projected to repeat their disappointing 2019 marks, as this is merely a backward-looking analysis. We need to account for additional factors when making a projection. But all else equal, the guy with an xHR/FB rate validating his disappointing HR/FB rate should be expected to have a worse chance of rebounding than the guy who suffered a disappointing actual mark, but underperformed his xHR/FB rate.

xHR/FB Rate Negative Validations
Player HR/FB xHR/FB HR/FB – xHR/FB
Luke Voit 21.0% 21.5% -0.5%
Jesus Aguilar 13.2% 12.9% 0.3%
David Peralta 14.6% 13.8% 0.8%
Matt Carpenter 12.1% 12.7% -0.6%
Yasiel Puig 13.9% 15.0% -1.1%
J.D. Martinez 23.4% 22.1% 1.3%

I guess it depends on who you ask as to whether Luke Voit’s 21% HR/FB rate was disappointing, about as expected, or great. If you had forgotten Voit’s 2018 exploits, let me remind you — he enjoyed one of those every-so-often incredible small sample runs after joining the Yankees. That included an absurd 40.5% HR/FB rate, which was nearly validated by a 30.8% xHR/FB rate (these marks don’t go much higher than that, so even though it’s still off nearly 10%, that’s as validated as it gets!). Obviously, Voit wasn’t going to repeat. But would he regress to that xHR/FB rate mark? Somewhere in the mid-20% range? As low as his minor league high mark of just 14.4%? Interestingly, he would likely hit more homers if he decided to pull more of his flies, as currently his fly ball pull rate is well below the league average.

Though Jesus Aguilar already showed us this kind of power in 2017, he was able to sustain it over a full season in 2018. Sadly, the magic disappeared in 2019, and xHR/FB rate tells us it wasn’t bad luck, just a straight loss of power. I would have happily speculated on a rebound cheaply this year, but I’m not nearly as excited about him in Miami, even if the new park dimensions will make it a little friendlier for hitters.

David Peralta’s power surged in 2018, though xHR/FB rate wasn’t totally buying it. Predictably, his HR/FB rate regressed back toward his previous years. However, he did deal with shoulder issues, which would easily explain the loss of power. I figured he would have suffered regression either way, but the shoulder could have accelerated the decline.

So it’s clear that 2018 is going to look like the outlier on Matt Carpenter’s record, as his xHR/FB rate dropped right back down to where it had been previously (outside 2016 when he drastically underperformed). Not only did he lose barrels, but he stopped pulling his flies, which is one of the major drivers of his newfound power from 2016-2018. There’s rebound potential here, but I want to see him get his fly ball pull rate back into the mid-20% range.

Nobody has signed Yasiel Puig yet?! Anyhow, like Carpenter, Puig lost both barrels and pulled flies. Early drafters might be able to snag him at a discount given that he’s still teamless, but obviously won’t remain so by the time the season begins.

J.D. Martinez spoiled us after posted two HR/FB rate marks around 30% in 2017 and 2018, but remember that before that (and after his breakout), he was merely good, not elite. Surprisingly, his barrel rate slipped below 40% for the first time on my spreadsheet going back to 2015, but he actually raised his fly ball pull rate to the highest mark during that period. Martinez missed some games here and there due to back issues, so it’s very possible that played a role in his decline.

We hoped you liked reading 2019 Review — xHR/FB Rate Negative Validations by Mike Podhorzer!

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Mike Podhorzer is the 2015 Fantasy Sports Writers Association Baseball Writer of the Year. He produces player projections using his own forecasting system and is the author of the eBook Projecting X 2.0: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. His projections helped him win the inaugural 2013 Tout Wars mixed draft league. Follow Mike on Twitter @MikePodhorzer and contact him via email.

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4 Comment authors
DiaTRIBEMike PodhorzerMario MendozaDarthSader9 Recent comment authors
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I would think that Voit’s proclivity for oppo flyballs is park driven.

Mario Mendoza
Mario Mendoza

Actually, it’s why the Yankees traded for him. He had lots of raw power but low HR% because he didn’t pull, which made him less valuable to Cards and more valuable to Yanks.


Voit was also hampered by injury for the back-half of the season. Prior to injury he was crushing the ball, but in his last 161 ABs after his return only hit 2 home runs. If injury related rather than “regression” or skill change related, I’d expect his xHR/FB to pick up again this year. I also assume/hope that the core surgery was a success and “Best shape of his life” talk is correct.