Really nice stuff Kyle, I looked up Carlos Zambrano, it is a very interesting. As I’ve closely watched him I’d never had realized his fb avg was dropping but clearly over time it is. It’s also interesting that throughout his time he’s had days where he was 3-4 mph avg faster than his “norm”, makes you wonder what the deal was.
It’s not worth getting into here, but the data that I use is raw PITCHf/x data and needs to be corrected. The release points are not consistent because camera systems installed in each park are not perfectly calibrated with each other. A 1-inch parallax error can cause serious problems as the ball crosses the plate, for example.
So this stuff is interesting to look at, but can’t be used for serious analysis. Fastball velocity should be more stable across parks, however, so that’s not a bad metric to use.
im pretty sure they use a camera and a computer system and it times from the release point as it croses the plate. It could be more complicated but im guessing all thats done is a distance formula like d=(x2-x1)2 + (y2-y1)2, they also have the time it was realesed from his hand and crossed the plate and then put it into a simple S=D/T formula to get the velocity