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I've never been a big exit velocity guy. Since it first entered our vernacular with the inception of Stacast in 2015, I've rarely factored it into my analysis of players.

It conveyed some measure of raw ability, maybe. Hitting the ball hard is certainly a skill. But my perception based on hundreds of casual observations was that the practical applications were limited.

I mean specifically with regard to the projecting of home runs, which are, in the modern game, the foundation upon which all other numbers are built. Sure, I could point to individual instances where a high average exit velocity helped raise the margin of error for an otherwise flawed hitter -- one with too high of a strikeout rate or too low of a launch angle, for example. But in terms of home runs, all that mattered was if the ball was hit hard enough to carry over the fence. And it turns out it didn't take much.

The funny thing about Statcast era, though, is that it's basically coincided with the juiced ball era. The former began in 2015, the latter in 2016, which means that prior to 2021, we didn't have a concept for exit velocity independent from the juiced ball.

What most defined that era wasn't just the prevalence of home runs but the distribution of them. The ease with which they left the yard made them more accessible to players of all shapes and sizes, to the point that everybody who was anybody had the potential for 20 or more.

You see where I'm going with this, right?

Sure, many of us theorized that the introduction of "deadened" baseballs last year would unlevel the playing field, but who would be most impacted and to what extent were matters of hot debate. It was only after the season, when I began my usual offseason evaluations, that the relationship began to take shape for me.

The players who most disappointed us in the home run department also didn't measure up in terms of average exit velocity. I'm not saying they had a down year. I'm saying they've always had middling exit velocities. It's just that the new ball made it so they could no longer get away with it.

That was my theory, anyway. To lock it in, I needed more data. Shoot, why not all the data? Exit velocity readings only date back to 2015, after all. So I created a scatterplot comparing average exit velocity and home runs for every qualifying batter over the past seven years, calculated the correlation each year, and well, looky here:

2021

0.47

2020

0.30

2019

0.38

2018

0.36

2017

0.38

2016

0.38

2015

0.44

For those unfamiliar with this sort of exercise, a higher decimal value means a stronger correlation, with a perfect relationship being an even 1.0. 

Sure enough, the relationship between exit velocity and home runs was much stronger with the end of the juiced ball era last year than in any year during it. In fact, the only other year on record that compares is 2015, which also happens to be the only other one that didn't coincide with the juiced ball era.

It's not that exit velocity was irrelevant. It's that those juicy balls disguised how relevant it was.  

You may point out that the relationship could still be stronger, and sure, that's true. I'm not saying average exit velocity is the single biggest determinant of a player's home run potential, but we've long known of the role that launch angle and barrel rate play. Plus, exit velocity is a more fundamental aspect of a player's identity, varying less over the course of his career. If we come to find out a certain threshold is prohibitive for a certain player, it's likely to remain so moving forward. 

And to be clear, it does seem to be more of a case-by-case thing than a magic number that applies to everyone.

This brings us to the particulars. You know how I mentioned those players who disappointed us in the home run department last year, with average exit velocity likely being the reason? We should probably get into those now lest you become too sanguine about their potential for a rebound. For some, it seems like the majority of early drafters already are.

(Note that the average exit velocity for those with 30-plus homers last year was in the 85th percentile while the average exit velocity for those with 20-29 was in the 75th percentile.)

Xander Bogaerts
BOS • SS • 2
EV percentile55
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He's a great hitter regardless, but it's looking all the more likely that the 33 homers he delivered in 2019 will be the high-water mark for his career.

Francisco Lindor
NYM • SS • 12
EV percentile75
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This sort of exit velocity should still result in a solid home run total, but maybe more like 20-25 than 30-35. And for a guy whose BABIP has always lagged because of his willingness to elevate, any slippage in the home run column could lead to steep decline in batting average, as we saw last year.

Alex Bregman
HOU • 3B • 2
EV percentile43
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Bregman's full-season pace last year was 21 home runs. He can probably do better than that, but he'll never match the 41 he hit in 2019. Even the 31 from the year before may be a stretch.

Anthony Rendon
LAA • 3B • 6
EV percentile45
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As if the mounting health concerns for the 31-year-old weren't bad enough, he was on pace for only 16 home runs when healthy last year. He hit a career-high 34 in 2019.

DJ LeMahieu
NYY • 2B • 26
EV percentile74
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The average exit velocity is respectable enough, but it plays down because of how little he puts the ball in the air. An outlier home run-to-fly ball rate is required for home run totals like he delivered in 2019 and 2020, and it appears unlikely with the new ball.

Trent Grisham
SD • CF • 2
EV percentile38
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The 2020 breakout was on pace for 27 home runs during the pandemic-shortened season. He hit 15 last year. Guess which is better supported by his exit velocity readings.

Yoan Moncada
CHW • 3B • 10
EV percentile67
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Moncada has produced superlative exit velocities in the past, but they've been all over the place so far in his career. Last year's may not be good enough to make him even a 20-homer guy.

Ke'Bryan Hayes
PIT • 3B • 13
EV percentile71
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The case of last year's struggles being tied to a wrist injury is less compelling when you consider he still delivered an above-average exit velocity. As with DJ LeMahieu, it would need to be elite for Hayes to overcome a 56.7 percent ground-ball rate.

Anthony Rizzo
NYY • 1B • 48
EV percentile67
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Last year's average exit velocity was actually the best Rizzo has ever delivered, and you see where it got him. Some of his worst readings actually came in the years he hit 30-plus homers, so it's likely the juiced ball helped.

Michael Conforto
NYM • RF • 30
EV percentile35
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Even in the year he hit 33 home runs, his exit velocity was only in the 50th percentile. Don't count on him being a 30-homer guy again.

Michael Brantley
HOU • LF • 23
EV percentile53
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During the juiced ball era, Brantley was a perennial candidate for 20-plus homers, but if last year is any indication, double digits are all he should be shooting for.

Trey Mancini
BAL • 1B • 16
EV percentile42
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Maybe the first year back from a major medical ordeal makes for an unfair assessment, but the 21 homers he hit last year are more in line with this exit velocity than the 35 he hit 2019. It doesn't help that the Orioles are moving their left field fence way back this year.

Cavan Biggio
TOR • 3B • 8
EV percentile42
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With apologies to Trent Grisham, Biggio may be the most obvious case of a batter being doomed by the new ball. Even in 2020, with the old ball, his xSLG was only .343.

Wil Myers
SD • RF • 5
EV percentile26
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Like Yoan Moncada, Myers' exit velocity readings have been all over the place during his career. Still, he went from a 44-homer pace in 2020 to just 17 homers last year. 

Jeff McNeil
NYM • 2B • 1
EV percentile28
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There was already skepticism surrounding McNeil's 23-homer 2019. You shouldn't count on him for even half that many moving forward.

Dominic Smith
NYM • LF • 2
EV percentile43
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Smith performed at a 32-homer pace during the pandemic-shortened 2020 only to then hit 11 in 2021. His career exit velocity average of 88.9 mph is only slightly above the MLB average of 88.3.