Further Adventures in Pull Rate

I don’t think I’m alone in my fascination with pulled fly balls. In fact, I know I’m not, because Alex Chamberlain wrote about them today too. These days, we’re practically drowning in data: exit velocities, launch angles, chase rates, aggression rates — the list goes on and on. There are so many different ways of thinking about exit velocity that you can read an entire great article about what they all mean. If you want to translate how hard someone hits the ball into how they’re likely to perform, there’s no shortage of instructive articles. But in that deluge of data, horizontal angle has been left out, for reasons both purposeful and accidental, and the unavailable is always interesting.
Earlier this month, I did some idle digging into what pull rate means for production on contact. The takeaway was, to be generous, middling. It seems like pulling your aerial contact results in better overall production on that contact, but the effect isn’t huge. Perhaps the more interesting takeaway was that xwOBA on these batted balls had a bias: the more pull-happy the hitter, the lower their xwOBA was on the balls they hit in the air. That was the case despite greater overall production on those balls.
That’s a weird little artifact, though I didn’t think too much of it because I kind of knew what it would say in advance. Every time I look at a dead pull fly ball hitter, they’re getting home runs out of batted balls that xwOBA hates. But that doesn’t mean the statistic is working incorrectly; it’s doing exactly what it says on the label by bucketing batted balls based on exit velocity and launch angle. Read the rest of this entry »