So one of the main points Voros originally made is that BABIP correlates very poorly from year to year. But we see that there is a relationship between BABIP and hit type, specifically LD% as it’s coefficient makes it the dominant term in your equation. Does this mean that LD% doesn’t correlate well year to year?
I get that LD% doesn’t stay consistent year to year, but why? If certain pitchers have extreme FB tendencies and others GB tendencies, why wouldn’t still other pitchers be more prone to a consistently high LD%?
Do any variables correlate to LD%? I’m thinking maybe pitch-type stats, like fastball%.
My theory – groundball and flyball rates are a function of fastball location. Groundball pitchers pitch down in the zone (usually with a two-seam fastball) and flyball pitchers pitch up in the zone (always with a four seam fastball). Both of these are by design – the guys who pitch up generally have good enough fastballs to get by hitters and rack up the strikeouts, and the guys who pitch down are just getting as many ground balls as they can.
To give up a lot of line drives, you’d have to consistently pitch in the middle of the strike zone, and really, that’s a pretty terrible idea, so pitchers don’t do it. Line drive rate is a function of missing location (either up or down), and mistakes have more variance.