Pitchers need to be followed closely for the earliest signs of fatigue (drop in velocity, change in mechanics, even small amounts of pain in the pitching elbow/shoulder, loss of control) and shut down quickly at the earliest warning signs.
Not to pick on you specifically, but for everyone in the "shut down at signs of fatigue" crowd, at what threshold should Romero be shut down? I mean, should he be shut down right now? If you look at his Pitch FX splits between May and June, it is pretty clear that compared to May:
- His fastball/sinker are both about 1MPH slower
- His changeup is about 1.5MPH slower
- His slider is breaking less
- His sinker is sinking less
- His changeup is flatter
None of these changes are very big, but they all point in the same direction - Romero's stuff is getting worse. Is it a sign of fatique/injury, or just normal seasonal wear-and-tear?
Any shutdown criteria involving abrupt changes in performance or mechanics is, in my opinion, too late; by that point the injury has already occurred. Noticeable changes to mechanics or velocity drops are trailing indicators - the arm/shoulder damage has already reached a point that the players performance is significantly effected. A lot of the early fatigue that pitchers deal with is not outwardly observable - the internal wear, tear and weakness on joints, muscles, ligaments and tendons all through the arm and shoulder.
This is why I prefer the idea of innings and pitch limits. While these artificial limits may be arbitrary in many ways, at least it is an objective measure. Trying to make judgments about "fatigue" is way more subjective - and often requires the honesty of a competitive athlete who has little incentive to be shut down. And additionally, at a certain level we understand that the act of pitching is a damaging to the human arm/shoulder. Putting limits along every usage axis - pitches/inning, pitches/game, innings/game, days between starts, innings/season, etc - provides a concrete and objective way to ensure there is rest/recovery time.
Edited by markos, 14 June 2018 - 11:23 AM.