A few weeks ago, I used exit velocity data to evaluate pitchers. Now I will use it to look at hitters.
I’m not sure I need to show you any statistics or data to prove that the harder the ball leaves the bat, the more likely it will result in a hit. Yes, bloops will fall in at times and line drives will get caught, but on average, I think this assumption holds.
You’ll see below that my assumption does hold when comparing exit velocity to on-base plus slugging percentage (OPS) among qualified hitters thus far in 2016. If you want a hit, hit the ball hard.
An increase of 1 mph in exit velocity will increase OPS by .021 points, on average* (in context– if a .900 OPS hitter increases his exit velocity from 91 to 92 mph, his OPS would increase to .921).
However, as you can see from the plot, not all hitters have their expected OPS. Many are under or over-performing based on how hard they’re hitting the ball. Let’s take a look at some of them.
Ryan Zimmerman is far and away the unluckiest hitter in baseball. His 93.7 mph average exit velocity ranks 9th in MLB, yet his .678 OPS is almost 200 points away from his predicted OPS. It’s also well below the major league average of .738. This unluckiness can be partially attributed to his .247 BABIP, which is the 7th lowest in MLB and well below the league average of .300. Zimmerman should seem some upward regression in the future.
Fielder, Norris, and Morrison also rank in the bottom ten in BABIP. Galvis is a bit different, though. His .275 BABIP isn’t awful, but he has a .125 ISO and 3.8% walk rate. This shows that most of his hits are singles and that he doesn’t walk– both of which aren’t included in a recipe for a high OPS. His upward regression may not be as likely as his unlucky counterparts.
Lets now take a look at the lucky guys:
Altuve stands out because of his speed factor– which isn’t taken into account when predicting what his OPS should be. He may be able to sustain a high OPS, despite a right-around-average exit velocity, by using his speed to accumulate infield singles and take the extra base on hits in the outfield. But Altuve isn’t just and speed and singles guy. His ISO has improved from .080 in 2013 to .213 in 2016. Instead of diving into statistics to attempt to explain this, I’d like to give all credit to adding a leg kick (@joshbrownie7). This combination of speed and power may justify Altuve’s high OPS despite his relatively low average exit velocity.
From 2011, Pre-leg kick days:
From 2016, leg-kick in action:
*r^2= 29%, p-value <.01. These show the correlation is statistically significant.