Links or some words of wisdom on correcting GameDay’s errors with identifying pitches. What spin types usually mean what?

Assume player is 4 and 2 in measurements and ball at 3.7 Should be a strike
but the standard pitch F/x strike zone puts it at high out of zone

To adjust the ball I use the equation: pz + (((3.5 – sz_top)+(1.5 -sz_bot))/2)
pz = vertical ball position
sz_top is top of batter’s stike zone
sz_bot is bottom of batter’s strike zone

so for the above example:

3.7 + (((3.5 – 4))/2)
3.7 + (((-0.5)(-0.5))/2)
3.7 + (-1/2)
3.2 is the new pz position – strike

Can you discuss this or how you normalize for batter’s height?

And I wish I could be there. Stupid work, always getting in the way of my fun.

Do you have pitcher splits for the windup vs the stretch? How much velocity (and even movement) does the average MLB pitcher lose from the windup vs the stretch?

Taking a glance at 2007 and 2008, the average pitcher is about a .730 – .740 OPS pitcher with the bases empty and a .770 – .780 OPS pitcher with men on, a .040 OPS difference. The K/BB ratio drops from about 2.32 – 2.35 to 1.69 – 1.7 from men on to bases empty. A little noise in that data with most relievers pitching exclusively from the stretch.

Some pitchers, however, perform significantly worse from the stretch, like Javier Vazquez, whose K/BB ratio drops from 4.18 to 2.53 and his OPS against rises over .080 points. Other pitchers, like Jair Jurrjens and Daisuke Matsuzaka actually improve their K/BB ratio and OPS against. Sample size can be an issue on these two, but the increased K/BB is less fluky than the OPS.

Do Vazquez’s pitches suffer more than average from the stretch? Do pitches like Jurrjens and Daisuke actually throw better stuff from the stretch?

I tend to use Gameday pitch classifications in a lot of cases – mostly because they’re all I have. I haven’t taken the time to study the physics of it all because most of what I look at hasn’t needed it.

But I do need pitch classifications and the Gameday ones are readily available in a way that other classifications aren’t. It would be great if someone were to release a daily feed of post-hoc classifications – provided MLBAM would be okay with that