Which hitters struck ball harder in 2016?

We officially have two seasons worth of Statcast™ data.
Mind you, it's not two full seasons, nor does it include every batted ball. But it's still highly useful data.
Although I continue to work on developing new equations with the data, we could all agree on one thing -- harder hit balls are better. This is especially true when considering fly balls and line drives. We care far more about this bucket of batted balls than grounders because I have calculated a correlation of 0.769 between average fly ball and line drive exit velocity (EV) and HR/FB rate.
So let's find out which fantasy relevant hitters enjoyed EV surges from 2015 to '16 and if those spikes resulted in HR/FB rate increases as well.

Overall, this group averaged 90.5 mph in EV in 2015 and boosted it 4.4 mph to 94.9 in 2016. That led to a dramatic jump in HR/FB rate, which more than doubled on average. Every single hitter increased their HR/FB rates in 2016, with four of the 10 increasing it by double digits. Of course, this is backwards looking, so just like any metric that we observe jump to new, higher levels, we have to assume some sort of regression the following year, absent any clear explanations. With that in mind, find out below which of these hitters fantasy owners should be targeting this season, and who is likely to take a step back.

Matt Joyce, Oakland A's: Joyce may have just had the quietest career year in history. Of course, it happened in just 293 plate appearances, which is essentially half a season, so there's a good reason no one was paying attention. Joyce had always been a decent hitter, combining excellent plate patience with above average power. But we know Joyce's performance in 2015 led to a desire to make changes to his swing. His ISO ended up jumping above .200 for the first time since '11, while his HR/FB rate spiked to nearly 10 percentage points higher than his previous career high. Now, Joyce becomes the primary right fielder against right-handed pitchers in Oakland. Of course, he's 32, has an injury history and can't hit lefties, but he makes for a perfect cheap speculation on the hopes these changes stick. In OBP leagues, he'll likely be a steal.
Matt Holliday, New York Yankees: Holliday appears here after his power disappeared in 2015 and he merely rebounded back to historical levels this past season. OK, so I don't technically know his historical EV levels before '15, but his power metrics hit their highest marks since '11. So much for aging. We could probably blame injuries on his poor '15 showing, and now it appears he's back to full health. Signing with the Yankees should increase his value, and although we still have to be wary of his age, he's in a good situation now for a full season repeat.
Sean Rodríguez, Atlanta Braves: Rodriguez pulled a Joyce, enjoying a career year after the age of 30. It included a career best ISO and wOBA and he earned himself at least part-time at-bats in Atlanta. Obviously, I would never expect a repeat of that 25 percent HR/FB rate, which was more than triple his 2015 mark and only the second time he has even been in double digits. But he was a big power prospect in the Minors, and who knows, maybe it just took him much longer to figure things out than it does for most. He makes for an interesting speculation in deep mixed and NL-only leagues.
Danny Espinosa, Los Angeles Angels: Espinosa's 2016 was a mixed bag, but both his fly-ball rate and HR/FB rate hit new highs, which led to a new career high homer total. Unfortunately, he now goes to a park that's fifth worst in baseball for left-handed home runs. It's also poor for right-handed home runs during those plate appearances, so the park move is a clear negative.

Jake Lamb, Arizona D-backs: Lamb made mechanical adjustments to his swing and broke out in a big way. Now he'll get a chance to play every day, rather than sit against lefties. Whether that's a good thing or not, we'll have to wait and see. But he owns a .256 wOBA and .141 ISO against southpaws, so he'll have to do better than that to benefit fantasy owners and actually prevent himself from getting benched against them. While I always say to expect regression, here's a perfect example of a clear explanation behind the power spike, so I'd project him to stay in the high teen range in HR/FB rate.
Kennys Vargas, Minnesota Twins: After playing in parts of three seasons now, Vargas will once again get a chance to win the every day DH job. While his EV jump is exciting, remember that both seasons are based off small sample sizes, as he recorded fewer than 200 plate appearances in both. Clearly, this man has power, but oddly his strikeout rate has risen, just as his swinging-strike rate has declined. The walk rate jump is intriguing, as it now matches with his Minor League days and suggests that maybe he's ready to contribute on a full-time basis. He's a nice sleeper, especially in OBP leagues.
Byron Buxton, Minnesota Twins: Everybody's favorite sleeper. Buxton struggled during his cup of coffee in 2015, then continued to struggle in '16…until September. That's when his BABIP ballooned to .370 and ISO to .366, all the while he continued to strike out a ton. The power spike seems to be a carry over from his Triple-A performance, and it almost seems like he's trying to become a different hitter after failing his first time around with the Twins. Obviously, he owns an exciting basket of skills, but all those strikeouts are seriously problematic, especially since he rarely walks. Although I'm just guessing here, I'm expecting him to become the trendiest of sleepers, which makes him far too costly to be worth the high risk.

Mike Moustakas, Kansas City Royals: It was only 113 plate appearances, but Moustakas did hint at what a powerful Moose might look like. I absolutely love how both his swinging-strike rate and strikeout rate have declined every single season since 2012. He's even going the opposite way, which is great for his BABIP potential, though not so much for his power. There's real intrigue here, as a power hitter with excellent contact skills, just missing the BABIP to hit .300. All the skills are trending in the right direction, and if he's healthy, you best not forget about him.
Victor Martinez, Detroit Tigers: I guess Martinez got healthy. Looking back, it's clear now that health was the issue in 2015, and in '16, he essentially proved that his huge 2014 was no fluke. Which is crazy, because he just finished his age 37 season. However, after a career worst strikeout rate, I'll continue to stay away.

Jean Segura, Seattle Mariners: Look at that, Segura showing some muscle! And we thought his 2013 season would go down as his best power year. Oops. Unfortunately, he now heads to Seattle, with a park that suppresses right-handed homers, after he has played in parks that boosts them. So Segura was already going to battle the regression monster, and now has to battle the park factor monster as well. He also won't hit .319 again. Don't blindly avoid him, but he may end up being overvalued on draft day.
A version of this article first appeared at FanGraphs.