There’s a lot to be curious about as the MLB works on an attempt to return. Beyond just the logistics of it all, questions abound as to how a shortened season will impact the performance of individual players and teams. Last night, one such question came to mind: Would older pitchers be at an advantage over a shortened season?
The logic, in my head, was that older pitchers know what they’re doing and are more prone to fatigue, while younger pitchers are learning the ropes and aren’t as fatigue-prone. I knew this was an oversimplification, but I thought it might be true, and I thought the implication might be significant in the event the MLB plays only half a season this year.
It was not true.
Nor was there any significant implication.
From FanGraphs, I took every pitcher from the last five years who hit the qualifying innings threshold in both the regular season’s first half (Opening Day-June 30th) and second half (July 1st-End), their age, and their FIP’s across said first and second halves, then compared the age with how FIP changed.
Nothing to see.
The r-squared came out to a comically miniscule .0002. The correlation coefficient was mildly negative (-.014, to be precise), but, as the r-squared showed, far from any sort of significance. From the looks of the graph, there’s no effect where “middle-aged” pitchers—those around 29 years old—see any better performance either (this held up when examining the median of each age—there was no significant trend from that).
Now, it’s still possible the initial hypothesis had a shred of truth to it, and it’s possible it was actively false, and it’s possible it was true to a point and false to a point. In more sensical words, it’s possible that age does have some predictive power on whether a pitcher improves or worsens as the season progresses, and the simplicity of this data pull masked something real. This was only pitchers who hit the innings threshold in both halves of the year, which implies a good degree of health and consistent performance. It was also only starting pitchers. It was also only measured as one half vs. the other, and the choice of where to draw that line was arbitrarily chosen to correspond more with games played than the season’s rhythm (June 30th is closer to Game 81 than the All-Star Break is). In short, this data pull doesn’t thoroughly debunk the age/improvement narrative. That said, it should make us skeptical of such a narrative if we do start hearing it in a month or two.
For what it’s worth.
