I have a different take on fatigue than I’ve seen others post. Any player – batter or pitcher – who has less than a ‘full season’ of PA162 or IP162 either didn’t start, platooned, got injured, or was a call-up at some point of the season. I think it’s safe to say that while these not-full-season-starters were playing, they were playing at 100%. So, why can’t we use them that way?
The perfect example is everybody’s favorite fatigue whipping boy from a few updates ago, Bob Milacki. In real life, in 1988 he started three times in a regular rotation slot, pitching 8, 8, and 9 innings. Try to use him like that in the Sim! You can’t; the Sim forces you to use him as a part-time Closer or RH Specialist, and stretch him out over multiple less than one inning appearances. So, the Sim does not let you use him as he was used in RL. What’s wrong with using him for three early-season starts, then just assume he got injured – waive him and claim a replacement? Or go ahead and save him for the end of the season? Sure, the old system where people would start him every other game through the playoffs didn’t work, but you should be able to use him in a normal rotation until his IPs are used up. I would make certain that in-game fatigue is tracked better, though: being able to use Milacki to throw every pitch in a 20-inning marathon is not my intention!
The same would apply to batters. If you have somebody with 450 PAs, you can use him as you want – burn through them all having him start every game then lose him when he hits his cap; rest him every so often to make those appearances last; etc. But you SHOULD be able to start him every game, without fatigue penalties, until he is used up. Similarly, your bench players shouldn’t go into a fatigue spiral after a couple early-season PH appearances. When you mouse-over their PAs, you should get a popup telling you what percentage of their maximum PAs (or IPs for pitchers, for that matter) they have used.
My two cents.