Trevor Story and Sample Size

Trevor Story hit another homer last night, his league-leading eighth home run of the season. That’s eight home runs in just 13 games, totaling 59 plate appearances. He also hit a double, giving him 12 extra base hits on the year; Josh Donaldson is the only other player in the majors in double-digits, and he has 10. At this point, it’s pretty clear that, while still a player with holes in his swing, Trevor Story hits the ball really hard when he does make contact.

Last night’s home run, for instance, was hit at 108 mph. It was the eighth ball he’s hit this year that left the bat with an exit velocity north of 105. For reference, here is the full list of the 13 players that already have eight or more balls hit at 105+.

Most 105+ Exit Velocities
Player Results Total Pitches
Carlos Gonzalez 15 215
Domingo Santana 13 230
Mark Trumbo 12 178
Manny Machado 11 175
Carlos Correa 10 189
Gregory Polanco 9 223
Josh Donaldson 9 248
Trevor Story 8 245
Giancarlo Stanton 8 219
J.D. Martinez 8 169
Bryce Harper 8 186
Danny Valencia 8 160
Jonathan Schoop 8 147

Maybe this should be a post about Carlos Gonzalez? Story is putting balls over the fence, but CarGo is absolutely crushing the ball right now. Anyway, his ridiculous teammates slugging performance aside, Story is mostly keeping company with some of the best sluggers in baseball, and then a few surprising names. Danny Valencia, for instance, is hitting .273/.333/.295 and has just one extra base hit so far, suggesting that he’s both been a bit unlucky so far but also that scorched ground balls — he’s at a 55% GB% for the season — are not as valuable as balls crushed in the air, and a reminder that exit velocity alone isn’t going to give us the whole picture.

Thankfully, MLB is now also releasing launch angle for every play, and Baseball Savant allows you to add launch angle as a filter in the Statcast search. So, if we look for just balls hit at 105 and with a launch angle of at least 20 degrees, we find a somewhat different leaderboard.

Most 105+ EV/20 Degree Angles
Player Results Total Pitches
David Ortiz 5 202
Trevor Story 5 245
Mark Trumbo 5 178
Josh Donaldson 5 248

These four players have combined to hit 20 balls in play with at least a 105 mph exit velocity and a greater than 20 degree launch angle; 15 of the 20 have gone over the fence. This is the kind of ball that is almost always a home run, and Story’s combination of an uppercut swing with the ability to hit the ball square suggests his power is not a fluke. You don’t fake your way onto a list with guys like Ortiz, Trumbo, and Donaldson, even in a baker’s dozen worth of games.

Of course, we don’t have a long history of Statcast data, so we can’t look back at Chris Shelton’s 2006 season and see how often he was crushing the ball back then. We don’t know how predictive this stuff is yet, though as Russell Carleton noted this morning, it appears that exit velocity is the kind of number that doesn’t need a massive sample size, and we know batted ball rates stabilize pretty quickly, so it would seem likely that launch angle is also going to be more meaningful earlier in the season than most results-based metrics.

And the fact that Story has hit five balls in just two weeks within this sweet spot for home runs suggests that he might just have some pretty special power for a middle infielder. For even more context on what these kinds of numbers can mean, here is the full list players who Statcast recorded at least 20 balls in play at 105+ EV/20 degrees last year.

Most 105+ EV/20 Degree Angles in 2015
Player Results Total Pitches % of Pitches
Chris Davis 42 2786 1.5%
J.D. Martinez 29 2605 1.1%
Nelson Cruz 29 2627 1.1%
Yoenis Cespedes 26 2722 1.0%
Mike Trout 26 2981 0.9%
Kris Bryant 25 2663 0.9%
David Ortiz 24 2485 1.0%
Paul Goldschmidt 23 2917 0.8%
Giancarlo Stanton 21 1221 1.7%
Edwin Encarnacion 21 2517 0.8%
Josh Donaldson 21 2817 0.8%
Miguel Cabrera 20 1985 1.0%

One thing is clear; Story isn’t going to keep hitting balls in this range at the same rate he has been so far. Stanton is the king of crushing baseballs, and if he couldn’t get over 1.7% of all pitches in this crushed ball sweet spot, then Story won’t stay over 2.0%. Realistically, even the best sluggers in the game are down closer to 1% of their pitches being put in play in this range, so despite his strong start, it’s probably not prudent to be projecting Story to be significantly above that going forward. But it’s also worth noting the kind of crowd he’s putting himself into; guys who hit the ball regularly in this exit velocity/launch angle range hit for a lot power, with no exceptions.

But because we’re dealing with such a small sample, you have to be careful to not get too over-exuberant, even with metrics like these that won’t take as long to reveal real skill.

For instance, last year, Brett Wallace hit five balls out of 428 pitches seen in this 105/20 range; at 1.2% of the pitches he saw last year, it wasn’t exactly the same kind of rate as Story has started off 2016, but it would have put him in that elite group as well if extrapolated out. He’s currently a bench player for one of the worst teams in baseball. Jarrett Parker hit four balls out of 226 pitches (1.8%) seen in this range, and he’s currently batting .119/.176/.143 in Triple-A. Hitting the ball hard for a few weeks isn’t a guarantee of success.

But at the same time, if Brett Wallace or Jarrett Parker could play shortstop, they’d probably be big leaguers. Both project as roughly league average hitters, and aren’t in the lineup because league average hitters with minimal defensive value aren’t that useful. League average hitters who can play shortstop? That’s another story entirely.

(Come on, you didn’t really expect to get through this whole post without a pun about his last name, did you?)

And right now, both ZIPS and Steamer think Story is something close to a league average hitter. Prior to the season, ZIPS had Story at an 86 wRC+, while Steamer checked in at 82. The rest-of-season ZIPS forecast, incorporating the results of the first 13 games, bumps Story’s wRC+ up to 94, while Steamer is more cautious, only going up to 87. Steamer thinks the sky-high strikeout rate is a bit more real than ZIPS does, while ZIPS puts a little more weight on the power, giving a 26 point spike in SLG as opposed to the 20 point increase that Steamer’s adjustment includes.

For additional context, I reached out to Dan Rosenheck, who has argued that by looking at the right kind of numbers within small samples, you can still identify significant changes even in spring training data. He’s also got Story’s SLG going up by roughly 20 points — he quoted a 19 point increase to me yesterday, but that was before Story had another double and a homer last night — and his rest of season forecast is in line with what ZIPS is projecting.

While no one wants to fall into the trap of overreacting to two weeks worth of results, we also need to keep in mind that our opinions of a player’s abilities need to be constantly updating as those players provide new information. Small sample data isn’t meaningless, and refusing to budge off a pre-season forecast when a player provides evidence that he’s better or worse than that forecast is an overly stubborn position.

For two weeks, Trevor Story has provided some real evidence that he can hit the ball exceptionally hard in the air. The other guys who are doing this as often as he is are elite sluggers, and the guys who did it regularly last year are mostly All-Star caliber first baseman or corner outfielders. While Story’s contact rate remains a significant problem, we should be getting close to the point where we’re not doubting his power too much anymore. Small sample size is a good refrain to keep in mind when looking at a player’s results, but as we move towards an era where we can measure a player’s raw abilities with greater precision, the time it takes to identify high-level talents will be diminished.

It’s early, and pitchers might yet figure out how to exploit the holes in Trevor Story’s swing, but at this point, it’s probably safe to say that his power is not a fluke. He won’t keep hitting homers at his current rate, but Trevor Story is probably going to hit a lot of dingers this year.

Dave is the Managing Editor of FanGraphs.

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The Ghost of Stephen Drews Bat
7 years ago

Quite the story.