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What is exit velocity (EV), and how to use EV for fantasy baseball analysis to predict HR/FB and BABIP on ground balls? Definition and meaning of exit velocity (EV).
Welcome, RotoBallers, to our overview of exit velocity (EV) for hitters. This article is a deeper dive into EV, and is part of our ongoing series "Using Sabermetrics for Fantasy Baseball."
In this article, we'll explore how EV can be used to predict BABIP and HR/FB using simple terminology anyone can understand. We'll also look at other factors that may trump EV when predicting player performance.
You can find our entire sabermetrics glossary, which includes links to many other sabermetric stats as part of this series. Each stat deep dive will be released over the next few days. Stay tuned!
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What Is Exit Velocity? Sabermetrics Glossary
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 use stats like Hard% and Soft% to forecast how a player should perform, expecting larger Hard% rates to produce larger BABIP and HR/FB figures. There is a relationship there, but it's not as clear-cut as you might think.
Pittsburgh's Oneil Cruz was responsible for the four hardest-hit balls in 2024, which were a 121.1 mph double, 120.5 mph double, 120.4 mph single, and 120.3 mph single. Giancarlo Stanton was the only other player in the top 10, taking fifth and sixth with 120 mph singles and slugging the hardest-hit homer at 119.9 mph. Cruz rounds out the top 10 with two more doubles and a 119.5 mph out.
Average exit velocity can be found on the Statcast leaderboards, while you need to use the Search function to find specific batted ball events. With that out of the way, here's a closer look at how the EV readings on Baseball Savant can give you an advantage in your fantasy leagues.
How To Use the Search Function on Baseball Savant
Baseball Savant's Search interface looks intimidating, and using it can be worse. For example, here is what my screen looked like during research for this article:
There are so many different things to toggle, most of which aren't relevant to your query. Speaking from experience, the best advice is to play with it until you get a feel for what toggles what.
It's also slow, so be prepared to wait a few minutes for search results even if you have an excellent internet connection. It may crash or give you random error messages, too, so reload the page and keep trying. You'll figure it out eventually, and there's a ton of fun, useful information hiding behind this awful interface.
Using Exit Velocity to Predict BABIP on Ground Balls
One way to determine how hard a given batter usually hits the ball is to look at his average exit velocity. The league average mark in 2024 was 88.8 mph, but that stat is of little value. The exit velocity on airborne balls (flies and line drives but not pop-ups) is all you need to evaluate HR/FB, while ground-ball exit velocity is the best indicator of a high BABIP on ground balls.
Sadly, many analysts use overall average exit velocity to evaluate HR/FB and BABIP. You really shouldn't do that unless you believe 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 86 mph on ground balls in 2024, and every mph above or below that figure is very important. For instance, hitters produced a batting average of just .165 on balls in the 83-85 mph bucket in 2024, dramatically affecting results even though the velocity isn't much lower than the league average.
Players who can be shifted should be expected to struggle on grounders regardless of EV, while faster players can punch above their weight. Unfortunately, Baseball Savant's leaderboards replaced ground-ball EV with EV50 (a context-agnostic average of the top half of a player's exit velocities) last season, forcing the use of Statcast to search for this type of analysis.
Using Exit Velocity to Predict HR/FB
In 2024, the average airborne exit velocity in Major League Baseball was 92.8 mph. All other things being equal, a batter with an average airborne EV would be expected to be near the league-average HR/FB. Seven qualified hitters matched the average EV on airborne batted balls last year: Mark Canha, Orlando Arcia, Jesse Winker, Alex Bregman, Michael Massey, Freddie Freeman, and Will Smith.
That's a lot of names, so let's limit our analysis to the most fantasy-relevant among them. Bregman's 11.5 percent HR/FB was just shy of the league's 11.6 percent mark and he's moving from a favorable park for right-handed power (105 HR factor per Statcast) to a neutral one (100). He may struggle to repeat last season's HR total with his volume-over-contact quality approach.
Similarly, Freeman managed just a 12.6 percent HR/FB despite Dodger Stadium's 116 Park Factor for left-handed homers. He had off-the-field issues on his mind, but Father Time may finally be catching up to the 35-year-old.
Smith's 11.1 percent HR/FB produced a 20-HR pace for the second straight season despite Dodger Stadium leading MLB in HR factor for RHB at 126. The 29-year-old isn't a big power threat anymore.
While airborne EV is an important power metric, 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 doing so.
Conclusion
Hitting the ball hard is 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 the home park 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!
More Sabermetrics & Statcast for Fantasy Baseball
