Weinstein: Exploring batted-ball run values and spray
From SABR member Max Weinstein at The Hardball Times on June 19, 2014:
If you have read my articles on batted balls and the like, this will come as no surprise: I don’t care for line drive percentage (LD%). As such, I’ve spent a significant amount of time thinking of better ways to measure a player’s performance on batted balls. If you want a recap, in a previous article I made the argument that H/Batted Ball Type was a better measure of a player’s batted ball distribution and performance. But to bring you up to speed, consult the following section:
Why no two Batted Balls look the same or should be treated as such
It’s no secret Line Drive, Ground Ball (GB), and Fly Ball (FB) classifications are faulty and have some major measurement errors. Until there is a standardization of the stringer data based on hit angle and velocity, we should be cautious with taking batted ball classifications at face value. The fine line between a FB and a LD is in the eye of the beholder, with many different eyes determining the classification among MLB’s 30 ballparks. So, the fact that LD%, GB%, and FB% don’t take into account classification biases by adjusting for park factors is concerning, being that a FB at one stadium can very well look different at another — despite looking the same on our spreadsheet.
Two, by using batted ball percentages we are assuming that all LD’s, FB’s, and GB’s are created equal. Binning each batted ball type into a percentage assumes that we believe they are created equal by not differentiating between a batted ball hit with authority and one blooped over an infielder’s head. While, yes, the public does not have HITf/x, and yes, we cannot differentiate batted balls by velocity—we can use proxies to help us separate batted balls into more accurate groups. Using Gameday data, it is possible to approximate the distance a ball was hit, the angle to the field it was hit, and (less accurately) which type of batted ball it was.
Read the full article here: http://www.hardballtimes.com/when-does-spray-data-become-reliable/
Originally published: June 19, 2014. Last Updated: June 19, 2014.