Pitcher fastballs peak at 29, decline quickly
The greatest thing for me as a fan the last few years is the explosion of great data researchers can use, from play-by-play information that helped build better defensive measures to the amazing stuff you can get out of MLB’s Pitch f/x system.
Like this, “Preliminary aging curve for fastball speed” by Josh Kalk. It’s early, yes, and Kalk discusses some potential limitations of the data, but go look at that. That’s the kind of data people — any of us — can use to figure stuff out.
It appears that until pitchers reach 28 or 29, they increase the speed on their fastball by about 1.5 mph. After 29, there is a rather sharp decline in fastball speed.
During the next five years, pitchers lose just over four mph.
No one ever knew this before this article. You had to run a team and be willing to devote ridiculous resources to get this, or be an outsider willing to invest several times more than that.
Thanks to Alex, whose email bumped this up the reading queue