Finding Power and Efficiency Through The “Well Hit Percentage” Statistic

The other day, I was scrolling through Twitter and came across a tweet from one of my favorite baseball writers, Eno Sarris of The Athletic. In this tweet, Eno talked about a relatively new statistic called “Well Hit Percentage”, which immediately sparked my interest and inspired me to learn more. Check out the tweet below:

While I’ve briefly heard about the “Well Hit Percentage” stat before, I wanted to dive deeper into its value to understand it better and begin crunching some numbers. So, this article is basically a brain dump of my research and data manipulation for you, the inquisitive reader. Please follow along and feel free to tweet at me with any questions that may come up. Good? Okay, let’s start from the top.

When Amazon Web Services implemented Statcast across Major League Baseball a few years ago, a multitude of new statistics and measurements began to prop up and assert their dominance. For example, you’ve probably heard countless mentions of “spin rate”, “catch probability”, or even “expected-statistics”, which are now widely used to evaluate players. Perhaps the most popular of these new statistics, however, are that of “launch angle” and “exit velocity”, which have taken the baseball world by storm.

You’ve probably heard of the many success stories associated with launch angle and exit velocity. J.D. Martinez, Kris Bryant, Josh Donaldson, and many others come to mind as players who have fully embraced the “Revolution” and dedicated themselves to hitting the ball in the air. Josh Donaldson breaks down this approach in the clip below around the 5:00 mark. He also leads with an awesome quote to set the stage, “if you’re 10 years old and your coach says to get on top of the ball, tell them ‘NO!’”

As Josh Donaldson illustrated in the clip, launch angle and exit velocity are both very important on their own, but must work together in harmony for a hitter to be as successful as possible. Think about it: let’s say Donaldson hits a ball with 100 mph of exit velocity, but makes contact at a low launch angle and punches the ball into the ground. Despite the high exit velocity, this ball has a good chance of being an easy ground ball out. This instance happened during an Indians game in September, check it out below.

On the opposite end of the spectrum, let’s say Donaldson hits a ball with a lofty launch angle, but only generates about 85-90 mph of exit velocity. Despite reaching an optimal launch angle, Donaldson has a good chance of only hitting a routine “can o’ corn” in these cases. This instance happened as well while Donaldson was with the Blue Jays in May. While Donaldson did hit a sacrifice fly in the clip below, take notice of how the low exit velocity off Donaldson’s bat resulted in an easy fly out.

Based on the instances above, we can confidently say that a hard hit ball is much less impactful without an optimal launch angle. Inversely, an optimal launch angle is much less impactful without a hard hit ball. Thus, players want to avoid hitting into one of those two instances as much as possible, and instead find a happy medium that maximizes both statistics (hard hit ball + optimal launch angle). The combination of these is where Eno Sarris’ tweet comes in, and is why “Well Hit Percentage” is becoming an increasingly popular statistic to use when evaluating hitters.

Specifically, “Well Hit Percentage” merges the optimal range of exit velocity (95+ mph) with the optimal range of launch angle (8-32 degrees). When a batter puts a ball in play with both of these ranges occurring harmoniously, good things happen. Home runs are crushed over the fence, line drives are hammered into the gaps, and runs are created in an extremely efficient manner. I mean, just see for yourself what happens when Josh Donaldson hits a ball in this “Well Hit” range during a September game against the Red Sox, facing Chris Sale.

As you can see, good things happen when the ball is struck within the “Well Hit” statistical range. Don’t just take my word for it though, let’s dive into some numbers. I took an export of 2017 and 2018 BaseballSavant data, queried for the “Well Hit Ball” ranges, and started to play with the data. My first question was how effective “Well Hit Balls” really were, and what approximate stat lines they produce across baseball on average. Well, check out the crazy results on the right:


Yes, you’re reading this chart correctly. The approximate batting average for all “Well Hit Balls” in 2018 was about .700, with ISO, wOBA, and xWOBA nearly touching 1.000! Oh, and don’t forget the gaudy 1.614 slugging here either. If you’re curious, the average exit velocity on “Well Hit Balls” was 102 mph, while the average launch angle was 19.2 degrees. Simply put, as these stats suggest, hitting a “Well Hit Ball” in play is extremely valuable for both individual and team success, which explains why hitters are now actively working to do it as much as possible.

Speaking of the hitters, let’s examine some individual statistics.

The table on the right shows the Top 20 hitters by “Well Hit Percentage” for 2018:Top_20_WHP

This percentage simply takes the total number of “Well Hit Balls” and divides it by the total number of balls in play. Please note that the minimum used for the following two tables was 200 total balls in play.

The results here are very interesting, as you can see many of the best hitters in the game filling out this top 20 list. This data further exhibits that if a hitter consistently makes contact within the “Well Hit” range of launch angle and exit velocity, success and production at the plate will quickly follow.

(In case you were curious, Josh Donaldson put up ~21% in “Well Hit %”, but did not qualify for this Top 20 table)


Now that we’ve examined the top 20 hitters, let’s scroll down and highlight the Bottom 20 hitters by “Well Hit Percentage” for 2018:Bottom_20_WHP 

Now these results are cool! Nearly every player in this list is known to be an extremely fast player, and most are very adept on defense as well. This, in a way, shows why baseball is so great.

While these players may not hit the ball as “Well” as other players in the league, they still add value to their respective teams through their speed and defensive prowess. Thus, there will always be a roster spot for these type of players. Also, just because these players have a low “Well Hit Percentage” now does not mean that will continue in the future. I mean, just look at Yonder Alonso‘s breakout season in 2017– maybe one of these players are next in line!

We’ll have to wait and see if that happens in 2019 though, as that’s all I have for now. Throughout the upcoming season, I’ll be sure to bring this back up as players make offseason swing adjustments—maybe I’ll make it into an ongoing series, who knows. Anyway, I hope you enjoyed my deep dive into “Well Hit Balls” and “Well Hit Percentages”, as it was incredibly interesting to research. This stat will definitely be one to monitor moving forward and I’m excited to see what happens next! Thanks again to Eno Sarris for the inspiration to research this stat in the first place. It is greatly appreciated!

Feel free to reach out to me on Twitter with any questions or comments: @HispanicHoosier

Feature photo credits: Keith Allison, Flickr

Evan Alvarez

Indiana University '17, Philadelphia native, breakfast food lover, and baseball fanatic. Always trying to learn more about the game each day. Follow me on twitter @HispanicHoosier and we can talk baseball (or breakfast foods)!

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