I think fatigue/stamina is still too enigmatic. Nothing ticks me off more than my well-managed, 100% team getting Deliveranced by a team half-full of guys at 85-95% (and, of course, those guys are the ones that seem to do all the damage, including RPs).
Which would you rather have: a team of 85% guys rolling hot, or a team of 100% guys rolling cool-average? I think we all know the answer, and that's a significant problem with this game.