Out with batting average, in with exit velocity
Baseball and statistics have gone hand in hand forever. First, it was batting average, home runs, and wins. Then came Moneyball and the sabermetric revolution, where teams began looking at more advanced statistics such as on-base percentage, OPS, DRS, wRC+, and WAR. In 2015, Major League Baseball installed an array of sensors around every major league stadium that tracks every movement of ball and player. The vast quantities of data generated from these sensors was called Statcast.
Phase I: collect data
At the time, we all knew that Statcast would make its mark on baseball, at least from a marketing perspective. It can tell us exactly how far a home run was hit. That's fun to know, but it goes further than that. Tracking exit velocity off the bat can discern slumps from plain bad luck. Route efficiency can shed light on an outfielder's play-to-play performance. In 2015 and 2016, analysts were so blown away by all of the available data that all they could really do was collect it and talk about individual points. However, in 2017, we're organized and ready to use it.
Phase II: change the game as we know it
Statcast isn't just a talking point as Giancarlo Stanton rounds the bases after hitting a 504 foot home run.
After two seasons of data collection, it is changing how front offices evaluate players, and even the very way we play the game. Launch angle and exit velocity data combined have already created a new statistic, called "barrels," which singles out the "best" hit baseballs that are most likely to generate success. From there, we can find that Miguel Cabrera was among the unluckiest hitters in baseball last season, as Cabrera's home stadium stole kept a disproportionate number of his barrels from going over the fence for home runs.
Players are taking notice of available Statcast data, as it has proven that fly balls are, in fact, better than ground balls. Daniel Murphy, who nearly won the 2016 NL MVP Award, credits Statcast data with helping him change his old approach to the new one that helped him post a 156 wRC+ in 2016 (in which 100 is average), or more conventionally, a .347 batting average with 25 home runs.
His teammate, Ryan Zimmerman, posted a 67 wRC+ (.218 batting average, 15 home runs), despite having the ninth best average exit velocity (93.7 MPH) in baseball, better than AL MVP Mike Trout (91.7), NL MVP Kris Bryant (89.8), and many other stars, per Baseball Savant.
Statcast found that he was hitting the ball at very low launch angles; i.e., he was hitting way too many ground balls, and pounding a ball at 93.7 miles per hour into the ground doesn't do much. In the past, analysts may have said that Zimmerman was "past his prime." Now we know, and more importantly, he knows, how he can increase his production late in his career.
Statcast is doing great things for outfield defense as well. Daren Willman over at Baseball Savant created a graph that compares an outfielder's distance from a batted ball to the ball's "hang time," or how long its been in the air.
From here, it tracks which balls a given fielder, say Mike Trout, allows to drop and which he catches. In 2017, MLB is rolling out a new stat created from the data mentioned above, which measures "catch probability" and "hit probability" given the constraints of distance and opportunity time.
The days of "that ball was hit pretty hard" and "that catch looked tough" are over. With Statcast, the eye test has been quantified, and baseball will never be the same.
