Looking into Differences in Exit Velocity

Statcast has revolutionized the way we look at batted-ball data. We have been spoiled with exit velocity, launch angle and so much more. After looking into this treasure trove of data, I began to wonder, how closely is a hitter’s overall production tied to their exit velocity? More specifically, I wanted to uncover whether production was tied to differences between Air EV and Ground EV. First, I calculated the difference between Air EV and Ground EV from Baseball Savant. Next, I filtered the list to only include those with at least 100 batted-ball events to not skew the sample. I also calculated AIR% by adding together LD% and FB% to see who is maximizing their contact and see who may need a change in approach.

This first chart illustrates which players have the largest difference between Air and Ground EV:

Player	Difference, Air EV and Ground EV (MPH)	AIR%
Byung-ho Park	17.3	58.7%
Nick Castellanos	13.6	68.6%
Brett Eibner	13.0	57.6%
Ryan Schimpf	12.9	80.4%
Mike Napoli	12.9	63.6%
Oswaldo Arcia	12.9	58.2%
Adam Duvall	12.5	66.1%
Brian Dozier	12.3	63.6%
Sean Rodriguez	12.3	60.2%
Brandon Belt	12.1	73.8%

Byung-ho Park leads the way by nearly 4 MPH, with a difference of 17.3 MPH. With the exception of Eibner, Park and Arcia, this is a list of hitters whose primary BIP type is FBs. Each of these hitters has an AIR% over 60%, with Ryan Schimpf pacing the group at an incredible 80%. With such a stark difference in EV, each these players should focus on hitting the ball in the air to maximize their overall production. For Park, Eibner and Arcia, putting the ball on the ground severely limits how often they can make harder contact. All things equal, hard contact is better than soft contact and these players should adjust their approach accordingly to maximize hard contact, which could help their overall production.

As we move on, the next chart displays players with the smallest differences in Air and Ground EV:

Player	Difference, Air EV and Ground EV	AIR%
Billy Burns	-2.4	46.8%
Melky Cabrera	-2.2	56.9%
Max Kepler	-1.5	52.8%
Matt Szczur	-1.4	57.4%
Martin Prado	-1.2	52.6%
Jose Peraza	-1	56.5%
Lorenzo Cain	-1	52.7%
Ryan Rua	-0.9	47.9%
Miguel Rojas	-0.7	46.0%
Tyler Holt	-0.5	48.0%

The speedy Billy Burns tops this list, complemented by a group of players no one will mistake for sluggers. This group comes with considerably less ceiling and overall production. Of this group, only three guys managed to post a league-average or better wRC+ (Prado, Cabrera and Peraza). Lorenzo Cain has been better in the past but was hampered by injuries this past year. Cain and the three previously mentioned provide the blueprint for how this profile can work. By spraying the ball and making enough contact, these guys maximize their limited power but have a razor-thin line between their bats being productive and unplayable.

As an aside, there was only one player who had zero difference in his EVs. The culprit? Nick Markakis, which for some reason makes perfect sense. Anyways!

So now that I have shown the extremes we can begin to answer the original question: does EV difference even matter for overall production? To find out, I ran a couple different tests. First, I took the data and divided them evenly into quarters. The results look like this:

Group	Average EV Difference	Average wRC+	Best Hitter
Top 25%	9.4	102	Joey Votto
25-50%	6.3	100	Mike Trout
50-75%	4.5	95	Miguel Cabrera
Bottom 25%	1.8	94	Daniel Murphy

The top 50% of hitters with large differences in EVs hit average or slightly better. Meanwhile, hitters in the bottom 50% produced slightly below average. To give each group a face, I took the best hitter by wRC+ and here we have four elite hitters. So far we have a very minor indication that says players with larger EV differences hit better than those with smaller differences. What we do not have is a concrete reason to disqualify a hitter from being elite based on their EV differences.

Next, I took the data and plotted players’ EV Differences and wRC+ to see if there was any correlation.  The graph is about as random as it gets with an R squared value of .022. This shows that there is a relationship between EV differences and overall offensive production but nothing significant.

All things equal, you probably take the guy with the larger differences but that does not guarantee any kind of success. We now know that their differences of how hard they hit balls in the air or on the ground do not preclude them from being elite. Hitting is both art and science and what we have learned today only reinforces that hitters can have very different profiles and still have excellent results.