Is it Legit? David Peralta's Breakout

We continue with our next edition of "Is It Legit?" to discuss another surprising breakout performer from the 2018 MLB season in order to assess his value heading into 2019.

With so many players seemingly becoming fantasy baseball darlings overnight, it can be challenging to sift through the multiple hype trains and determine which players are actually expected to produce similar, or even better, numbers the following year.

Arizona Diamondbacks outfielder David Peralta posted a .293 batting average and .352 on-base percentage last season, identical to what he posted in 2017. However, Peralta's power surged in 2018, going from 14 home runs and a .444 SLG in 2017 to 30 bombs and a .516 SLG in 2018. What happened, and what kind of power output can we expect from Peralta in 2019?

Can Peralta Repeat in 2019?

Breakout probably isn't the right word for what Peralta did in 2018. After all, the majority of his stats look very similar to his 2017 output. His batting average and on-base percentage are identical. His walk rate is nearly the same, and his strikeout rate actually got worse. He scored seven fewer runs and had four less stolen bases.

However, anytime a player doubles their home run total in a similar number of at-bats, it is worth paying attention to. Peralta hit 14 home runs in 140 games in 2017 but blasted an even 30 in only six more games last season. His ISO went from .150 to .223, and his slugging climbed from .444 to .516.

Peralta's 2017 numbers are useful, albeit kinda boring, for fantasy purposes. His 2018 numbers make him a highly-touted outfielder. Where will he fall in 2019? Likely - somewhere in the middle.

Looking at his batted ball profile, it is easy to see what caused Peralta's meteoric rise in dingers: he absolutely smoked the ball when he made contact. Fangraphs pegged him for a ridiculous 48.6% hard-hit rate, and statcast backed it up with a 45.7% mark and a 91.5 mph exit velocity, both in the top-ten percent of the league. Basically, the dude crushed the ball last season.

With a higher hard-hit rate often comes an increase in ground ball rate, as it is much easier to hit the ball hard on the ground than it is in the air. That wasn't the case for Peralta, who actually decreased his ground ball rate from 55.7% to 50.1% even with the nearly 17% increase to his hard-hit rate. Wow.

That certainly justifies his 23.4% HR/FB rate, which would otherwise look obscene.

There are still some concerns, however. xStats, which uses launch angle and exit velocity to determine a player's expected output, puts Peralta at a .280/.351/.477 slash with 25 home runs in 2018 - not bad but a tick below his actual output. Plus, Peralta's increase in strikeouts (from 16.3% to 20.2%) is a bit concerning, as is his drop in steals. With more power comes more strikeouts, and the stolen bases are only a small difference. Still - Peralta's profile has shifted to a more all-or-nothing approach, and while his BA/OBP is still strong, it wouldn't be shocking to see them take a hit if he keeps swinging for the fences.

Speaking of the fences, there's not a lot to support Peralta mashing 30 dingers again in 2019. STEAMER projects him for 23, which feels more likely considering his history. Plus, the Arizona lineup has taken a massive hit with the loss of Paul Goldschmidt and A.J. Pollock. RBI opportunities will be harder to come by, making Peralta a less desirable fantasy asset.

I'm still keen on Peralta as a solid outfielder in the middle rounds, but I expect closer to 25 home runs, 70 RBI, and a .280/.350 slash line. That's nothing to shake your head at - even if that 30 home run marker ends up as a career outlier.

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