The question of how pitchers age is paramount to players and front offices. “Stuff,” the colloquial term for raw talent throwing the baseball, can really be boiled down to velocity and movement (if we really wanted to oversimplify things). PITCHf/x gives us an opportunity to use big data to estimate “stuff” by looking at measurements of velocity and movement. We can use the copious data collected to estimate what “stuff” we can expect from pitchers as they pass the dreaded 30-years-old mark and beyond.
PITCHf/x reports movement in horizontal and vertical vectors. Horizontal movement (Hmov) is the right or left movement of the pitch compared to the expected trajectory without air resistance. A positive value is away from a right-handed batter. Vertical movement (Vmov) is the amount the ball moves up or down relative to the expected drop in a vacuum. A positive value means the ball dropped less than would be expected without effective spin.
It has been established that fastball velocity tends to decrease with age, but movement trends haven’t been looked at before. Might aging pitchers compensate their decrease in velocity with an increase in movement? Or does time steal away effective spin as well?
Let’s find out.
I collected all PITCHf/x data from every pitcher with at least 300 innings pitched from 2007 to 2018 (n=537). Data was aged based on the age of the player on April 1st of the corresponding season. Velocity, horizontal movement, and vertical movement were averaged for each age and graphed. The horizontal axis of left-handed pitchers was flipped so right and left-handed data could be analyzed together.
I then took out the top starters by WAR (n=63), according to FanGraphs, from 2007 to 2018 and graphed their data separately.
Results/Discussion: Graphs are available by clicking on the links below, and raw data available in tables at the end of this post. Read the rest of this entry »