Pitcher Batted Ball Distance Correlation

Yesterday, I shared the year-to-year correlations of the three variables that comprise my current xHR/FB rate formula. We now know that batted ball distance is fairly stable each season, which is excellent news for those using it to project future player performance. But what led me to gather the data and perform the calculations was actually a request to look into the pitcher side of the ledger.

By now, you’re all familiar with the home run + fly ball distance leaderboard we reference data from so often here. But did you know there’s a pitcher version as well? It’s true! It provides the exact same data and goes back to 2007 also. However, there has been precious little done with this data. In fact, I cannot recall reading anything at all about that leaderboard. So it’s time to change that.

Just like with the hitter leaderboard, I collected the data from each season, plopped it into Excel, lined up the season and prior season, and politely asked Excel to tell me the correlation. There were 970 player season pairs in my data set. And the YoY correlation was…

0.308

And now for a pretty plot of the results:

Surprised? Not surprised? I’m not. A lot of sabermetric research over the last decade has led us to believe that a pitcher has limited control over what happens to a ball once it’s put into play. While a pitcher could certainly control what type of batted ball he allows (grounder, fly, etc.), that’s really all he could do once the ball leaves his hand, for the most part. The YoY correlation of a hitter’s batted ball distance is more than double that of a pitcher’s.

But wait! 0.308 isn’t nothing. And there is very clearly an upward sloping line, which tells us there’s something going on here. To be perfectly honest, I expected the correlation to be lower. Perhaps much lower. I kind of wanted it to be nil so I could just ignore the data and continue to believe DIPS theory to the extreme. It’s easier that way. But this does suggest it’s something worth paying attention to, at least a little bit.

Obviously, hitters have significantly more control over how far the ball is hit. But pitchers do influence this number, just not to a very high degree. Armed with this data, and learning that a pitcher’s batted ball distance allowed is not totally meaningful noise that jumps around every year, there is seemingly lots more we could do. Where we go from here, I am not entirely sure, but it could help with the next step of trying to further explain BABIP and HR/FB rate differences.