THE BOOK--Playing The Percentages In Baseball

Monday, April 14, 2008

Fastball aging curves

Rally and Sal talk about fastball speeds, and what they can tell us.  I wrote on ballhype:

Age and injuries would be the biggest cause of a dropoff.  I would guess that if you looked at pitchers only in their 20s, the fastball in 2006 would be almost identical to his 2007.  Can you confirm? Simply put, you need an age parameter. I’d also love to see it for the other pitch types. And the “split” in pitches thrown (% of pitches that are fastballs, etc). Lots of great stuff here.

And in Rally’s study, selection bias will certainly play a part here (prospects who lose their fastball speeds are much less likely to get any playing time in MLB, thereby restricting our sample pool).