RADIO
Rick Lucks discusses how exit velocity (EV) can be used to predict a fantasy baseball player's future performance in his ongoing series on making sabermetrics more accessible to fantasy managers.
If you've watched a baseball broadcast in the Statcast Era, you have undoubtedly noticed the broadcasters commenting on a batted ball's exit velocity, or EV. Many have taken to using stats like Hard% and Soft% to forecast how a player should be performing, expecting larger Hard% rates to produce larger BABIP and HR/FB figures. There is a relationship there, but it is not as clear-cut as you might think.
The hardest batted ball of the 2021 season was struck by Giancarlo Stanton. It was clocked at 122.2 mph, but Stanton grounded into a double play for his efforts. Stanton was also responsible for the next five highest exit velocities of the season, logging four singles and an out on them. The hardest-hit home run was the seventh-hardest hit ball overall: a 119.6 mph blast off of the bat of Manny Machado. While higher exit velocity figures support offensive performance, you need to use other tools as well to accurately assess a player's performance.
Most of the data in this article comes from the "Search" function on Baseball Savant, but be warned that its interface is far from intuitive and that it can take several minutes to load your search results even with a strong internet connection. You may also get random error messages just because. With that out of the way, let's take a closer look at how the EV readings on Baseball Savant can give you an advantage in your fantasy leagues.
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How can I use EV to predict BABIP on ground balls?
The best way to get a feel for how hard a given batter usually hits the ball is to look at his average exit velocity. The league average mark in 2021 was 88.1 mph, but that stat is of little value. The exit velocity on airborne balls (both flies and line drives but not including pop-ups) is all you need when evaluating a player's HR/FB rate, while ground ball exit velocity is the best indicator of a high BABIP on ground balls. The two metrics should seldom intersect, but a lot of analysts ignore context and use overall average exit velocity to evaluate both HR/FB and BABIP.
You really shouldn't do that unless you believe that a grounder has a chance of going over the fence. Hard% is even worse, as it assumes that all batted balls of at least 95 mph are equal and makes no attempt to differentiate ground balls from airborne ones. So how do you figure out what's useful among these sabermetric measures? As always, the answer lies in placing these numbers in their proper context.
Major league batters averaged an EV of 84.4 mph on ground balls in 2021, and every mph above or below that figure is very important. For instance, hitters produced a batting average of just .161 on balls in the 80-82 mph bucket in 2021, dramatically affecting results even though the velocity doesn't seem that much lower than the league average.
As we've previously seen, players who can be shifted should be expected to struggle on grounders regardless of EV, while faster players can punch above their weight. Much like broader BABIP, it is a good idea to compare a player's current BABIP on ground balls to his previous work to account for these factors. As such, average exit velocity on grounders should be seen as one piece of a larger puzzle instead of the end of your BABIP analysis.
How can I use EV to predict HR/FB?
In 2021, the average airborne exit velocity in Major League Baseball was 93 mph. All other things being equal, a batter with an average airborne EV in the same area would be expected to be near the league-average HR/FB. Two qualified hitters posted an average airborne EV equal to the league average: Yandy Diaz and Nathaniel Lowe. Diaz posted a HR/FB of 10.6%, so he should be due for some positive regression. Lowe's was 16.5%, so negative regression should be expected holding all other variables constant.
While airborne EV is an important power metric to look at, other variables can prove more important. Ironically, airborne exit velocity's most important use may be to confirm whether a player besting his career BABIP on fly balls and/or line drives can continue to do so.
Conclusion
Hitting the ball hard is obviously a good thing, but limiting your fantasy analysis to just exit velocity is asking for trouble. Variables such as strong pull tendencies and foot speed can trump raw EV in a player's BABIP on ground balls, while home park, launch angle, and Pull% can all support elevated HR/FB figures even if the EV doesn't. Oh, and for the love of the fantasy baseball gods, please don't use Hard% for anything. Stay tuned for more tips on how to leverage sabermetrics in your fantasy analysis!
