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 so-called 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 2019 season was struck by Giancarlo Stanton. It was clocked at 120.6 mph, but Stanton only recorded a single for his efforts. The hardest-hit home run was a three-way tie at 118.3 mph: Gary Sanchez, Peter Alonso, and Aristides Aquino. Aaron Judge's best EV of the season was clocked at 118.1 mph and made an out. While higher exit velocity figures support offensive performance, you need to use other tools as well to accurately assess a player's performance.
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 2019 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 84.8 mph on ground balls in 2019, and every mph above or below that figure is very important. For instance, hitters produced a batting average of just .150 on balls in the 80-82 mph bucket in 2019, while batted balls at 85 mph or above produced a .347 batting 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 career mark 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 2019, the average airborne exit velocity in Major League Baseball was 92.7 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. Unfortunately, nobody of fantasy interest matched the exact MLB average in 2019.
If we increase the threshold to 92.8 mph, we get a bunch of fun names to work with: Gleyber Torres (21.5% HR/FB), Charlie Blackmon (17.7%), Jose Altuve (23.3%), and Jonathan Villar (16.7%). By exit velocity alone, all four of these guys were due for significant regression that could adversely affect their fantasy value. Sure enough, all four of them had down 2020 campaigns.
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.
If you'd like to learn how to interpret more statistics for a fantasy advantage, please check out our other articles on the topic.
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