RP3 Fatigue questions

I have 3 RP3's. It's the end of the season and one is now entering every game at F0. The other two enter at F4- F0 most times. Why does this happen if they have not pitched in the series and/ or not pitched in the previous games? Isn't fatigue based upon recent innings pitched? Or is there a season limit to innings? Not sure why this one in particular has been entering games for awhile at F0 without fail. This is not good for the playoffs.

Post a link to your team, it might be helpful.

Not sure if this applies, but there is a bug in the system (one among dozens, but SOM doesn't care, they just cash in, thank you good luck).

The bug in question: the rest days between the series rest only starting pitchers. They don't rest relievers. No matter how many days separate the series.

i've never noticed that before maybe that's why HAL's Bullpen Management is so screwed up?