Who Are Baseball's Biggest Statcast Overachievers?

These three players have been productive to start the season, but their exit velocities and launch angles suggest their hot starts are unlikely to continue.

Statcast is the new, fun toy in baseball, and it is everywhere.

Launch angle and exit velocity maps are in our Twitter feeds, and route efficiency numbers are on our television sets. It’s good to have new ways to quantify things, and the possibilities for new avenues of analysis are exciting.

One of these new areas of analysis is redefining contact quality and, by extension, luck. Andrew Perpetua has done yeoman’s work at by taking exit velocities and launch angles and deriving expected value.

This past winter, Perpetua found that expected Weighted On-Base Average (xwOBA) outperforms actual wOBA in terms of predicting next-season wOBA. This makes it a good tool for measuring the sustainability of a hot or cold streak.

With that in mind, here are the three players in the big leagues who have a wOBA that is more than 50 points higher than their xOBA.

Didi Gregorius, New York Yankees

Actual wOBA -- .341

Expected wOBA -- .277

Difference -- 0.64

Among the 211 players with at least 200 plate appearances, no one’s expected and actual performances deviate more than Didi Gregorius’. He has provided above-average value to date, but his xOBA is below average, even by shortstops standards.

Some of this is the result of being a lefty hitter at Yankee Stadium, but that is only part of it. The next highest Bronx Bombers on the xwOBA overachievers list are Starlin Castro (2nd, 32-point difference) and Brett Gardner (26th, 27-point difference).

The bigger culprit is his average exit velocity, which is just 84.3 miles per hour (MPH) and 2.6 MPH slower than the big league average.

Despite the below-average terminal velocity and just a 17.4% line drive rate, Gregorius is sporting a .329 BABIP. We can safely expect this to regress (he has never before posted a BABIP above .300 for a full MLB campaign).

He also has the 28th-biggest gap between his Isolated Power Rate and Expected ISO.

Gregorius has actually shown a reverse platoon split over the last two years, and the batted-ball data this season suggests this is legitimate (despite not showing this kind of split over his first four big league seasons). Against lefties, his xwOBA is 5.4% better than league average while it is nearly 20% worse than average against opposite-handed pitchers. This is roughly portional to his “real” wRC+ splits (39% better than average versus lefties and 4% better than average against righties), only worse.

He has already been worth about 2.0 wins for the New York Yankees, thanks to the combination of the positive results at the plate at a premium position and good defense. In terms of the former, though, the results seem to be outpacing the process, and it is unlikely to continue.

FanGraphs projects Gregorius to post a .313 wOBA for the rest of the season, which makes intuitive sense. It is in line with his career mark of .310 and roughly halfway between his to-date level of performance and his expected output.

Zack Cozart, Cincinnati Reds

Actual wOBA -- .405

Expected wOBA -- .349

Difference -- .056

Speaking of good defensive shortstops who have provided offensive value in a hitters park, Zack Cozart has already had a career year in terms of fWAR (2.8), thanks in large part to a wOBA that is 113 points higher than his career average coming into the season.

It is incredibly obvious he will not be able to keep this up -- 31-year-olds don't often flip a switch like this -- but unlike Gregorius, there are actually some encouraging signs in his batted-ball profile.

An inability to do damage against righties had held Cozart back previously as he came into the season with a .310 wOBA against lefties and a .287 mark against righties. He had a low strikeout rate against righties (16.4%), but he struggled on batted balls (.273 BABIP) and did not hit for much power (.130 Isolated Power, or ISO).

In 2017, prior to going on the disabled list with a quadriceps injury, he posted a .390 wOBA against righties. Cozart coupled a 19.1% strikeout rate and 13.6% walk rate against them with a .346 BABIP and .235 ISO.

The ISO in particular looks like a fluke, as his xISO against righties is 81 points lower. Still, if we strip away luck/randomness, Cozart has still been an above-average hitter against same-sided pitching, as his xwOBA is .337 (thanks to his strikeout rate, walk rate and .306 xBABIP).

He has coupled his increased production against righties by absolutely mashing lefties to the tune of a .456 wOBA and .390 xwOBA. In the split, he has solid walk and strikeout rates, a staggering .372 xBABIP and a .203 xISO. Still, his actual ISO against lefties (.265) is far outpacing his Statcast-implied power.

Against all pitching, the 77-point gap between his ISO (.242) and xISO (.165) is the largest in the majors. While the power will probably not be sustained -- particularly not against righties -- he may be able to run a BABIP closer to league average going forward.

Cozart had never recorded a BABIP higher than .285 over the course of a full big league season. While he certainly will not maintain a .367 mark, his solid Statcast numbers suggest that perhaps he can, at the very least, get closer to the big league average going forward.

FanGraphs projections he will post a .292 BABIP and .321 wOBA going forward, but provided he shows no ill effects from the injury, it is not hard to see him beating these numbers. Plus, even if he doesn’t, that projected wOBA is still better than that of an average shortstop.

Michael Taylor, Washington Nationals

Actual wOBA -- .346

Expected wOBA -- .295

Difference -- .051

After two seasons of being a glove-first player, Michael Taylor has been providing value with his bat this season. But if the Statcast data is any indication, we should not expect it to continue.

Taylor has a career 32.1% strikeout rate and 6.1% walk rate, meaning he has had to do a ton of damage on contact to be a productive offensive player. Over his first 791 big league plate appearances, this has not been the case. While his .315 BABIP was solid, it was coupled with a meager .135 ISO.

This season, the strikeout and walk rates have gotten worse (33.0% and 4.5%, respectively), but he has been better when he does make contact. His .372 BABIP is obviously due to regress, but given his .311 xBABIP and top-class speed, it would be fair to expect his BABIP to remain north of .300 going forward.

In terms of power, his .244 ISO marks a dramatic increase from his previous marks, but there does seem to be improvement in terms of process here. His xISO is a respectable .198 and seems driven by an increase in launch angle. Taylor came into the season with a 30.7% fly-ball rate but is now hitting a fly on 36.5% of his batted balls, putting him above the big league average for the first time in his career.

In 2015 and 2016, his average launch angle was 7.6 degrees, and it is 11.3 degrees this year, according to Baseball Savant.

Still, despite the solid xISO and xBABIP, his xwOBA is still way below average, because his plate discipline remains poor. The improved contact quality is nice, but if he does not get to work on his strikeout and walk rates, his offensive value will be severely limited.