This 1000000000000000000000000000000%
I was going to make a thread about this very thing, but this is the #1 pet peeve I have with the last iterations of this game. The AI bullpen logic needs to change in 2020. Seems like energy affects nothing. Confidence seems to be the only factor in performance. It doesn't matter if the energy is gone, the confidence up? He will pitch as long as the AI decides to take him out. It's irritating.
You are spot on with the being exhausted part. The confidence thing is so stupid and a bit illogical. If my arm is weak because the AI decided to have the pitcher throw 150 pitches (just throwing out a number) because his confidence is at 90% in the 4th inning, it has to have some affect, but not on this game. I know what I just typed is exaggerated, but you get what I am saying. It's illogical and unrealistic.