The rise of technology in sports, particularly baseball, is having dramatic effects on how professional organizations approach the game. One of the newest and most upcoming statistics that point to how to hit more home runs and extra-base hits is exit velocity. Exit velocity is the speed with which the ball leaves the bat. Baseball’s most prolific home run and extra-base hitters typically average an exit velocity of 90+ mph, while the MLB average in this category comes in at around 87 mph. Players like Nationals’ second baseman Daniel Murphy are constantly tweaking their swings to find the motion that gives them the best chance of driving the ball with an ideal exit velocity. “You want to hit the ball optimally about 25 degrees at 98 mph,” Murphy said, “those are home runs.” Over the past three seasons, Murphy has been adjusting his swing constantly to hit the ball the way he wants. Mets hitting coach Kevin Long has helped Murphy to move up on the plate and reduce the disconnect between his back elbow and back hip. It’s been working, too. His exit velocity increased from 90.8 in 2015 to 91.3 in 2016 to 92.3 through the first month of 2017, resulting in a higher percentage of line drives. He has made the All Star team in 3 of the past 4 seasons, something he had never done before.
The scatterplot below shows wRC+ vs. exit velocity. wRC+ (weighted runs created plus) is a measure of a player’s offensive value using how many runs he contributes to his team relative to other players while taking park effects into account. The 20 players in the chart correspond to the 10 players with the highest exit velocities in 2017 and the 10 players with the lowest exit velocities in 2017 among all qualified hitters. There is a stark difference between the two groups. Generally speaking, those with higher exit velocities create more runs for their team than the league average with two exceptions, Kendrys Morales and Miguel Cabrera, who have been relatively unlucky this year, coming in with with BABIPs lower than their career averages.
The moral of the story is that as exit velocity increases, so does the player’s likelihood to produce more runs for his team. Thus, it is worth it for hitting coaches to consider taking a similar approach to Kevin Long and considering how to help his players hit the ball harder. In addition to Long and Murphy’s efforts, the Tampa Bay Rays have been at the forefront of using Statcast. They observed that almost all home runs are hit with a 95+ mph exit velocity (see the figure to the right). After working on hitting the ball harder and in the air throughout spring training, they ranked 3rd in hits, 2nd in home runs, 5th in batting average, 6th in slugging, and 5th in exit velocity among the fly balls they hit. At the time, outfielder Corey Dickerson was slumping but was still managing a 143 wRC+ against right-handed pitchers largely due to his average of a 94.9 mph exit velocity on fly balls.
Baseball has been and always will be a numbers game. With advances made in technology in recent years, MLB released Statcast in all 30 ballparks in 2015. With Statcast, teams can track a plethora of new stats in pitching, hitting, fielding, baserunning, and more. Among the hitting category is exit velocity. Every single team has access to this relatively new statistic that has the power to help them adapt into a stronger offensive unit since it can predict the offensive value of every single player. The teams that take advantage of these statistics and take the time to help their players adapt their swings will undoubtedly be the ones who reap the rewards.