The main problem I’ve run into with my analysis is that, as I divide the data, the sample sizes get smaller. With only 947 samples with which to work, the numbers get scattered quickly. For this chart, I’m only looking at the player’s age and his BMI.
The main number that jumps out is the increased Average Disabled List Expectancy (ADLE) for pitchers with a high BMI. More specifically, high-BMI pitchers appear to break down more rapidly around age 29.
Next, I divided the pool of pitchers up into those who went to college and those who didn’t:
Take a look at the pitchers who attended college. In general, they go on the DL at a below-average clip when they are young, but, as they age, they head to the DL at a faster rate. College pitchers that make it as a starter in the majors have shown that they are able to pitch under a decent workload, but that workload catches up with them when they turn 29.
Using the preceding data, here’s a list of pitchers who fall into our “middle-aged,” high-BMI category. These players as a group are as likely to see significant disabled-list time compared with younger pitchers with the same BMI. Heavier pitchers begin to breakdown when they turn 29. The players’ bodies seem not to be able to handle the additional weight they are carrying. I never expected a player’s weight to matter so much. With the available data, it certainly does.
With the limited amount of data, it is too early to draw too many conclusions for starting pitchers. I will be doing further research on relief pitchers and position players to see what trends exist with those players. With that said, here are the 29- to 32-year olds:
As of right now, at least one of these players will start the 2011 season on the DL: Johan Santana. I’ll be closely watching how this group holds up during the season.
Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won three FSWA Awards including on for his MASH series. In his first two seasons in Tout Wars, he's won the H2H league and mixed auction league. Follow him on Twitter @jeffwzimmerman.