The replies from DKC, llad and quietman are perfect analysis of my question. On my D1AA team, I have DL starters with stamina that ranges from 51 to 70. In the 4th quarter of one of my recent games, during a long drive by the opponent, they all fatigued and turned yellow within one play of each other. That would make sense if the game is monitoring relative fatigue for substitutions, but overall fatigue for the game should have seen my 51 guys tired from play 3 or 4 and the 70 guy at about play 8 - 9. I still have a question about whether these levels really have any effect on the players ability, or is the fatigue factor just a detriment because your subs come in. If it doesn't have a play ability effect, until the update you should then just play your starters until they can hardly crawl.