That is a very good point. I really wonder if the CPU is going to be smart enough to say hey my WR is yellow/red maybe I should take him out and put someone fresh in.
I know they had a sub system in franchise mode but I dont know if it worked. It was near the pass to run ratio and the type of defense you could pick menus. It was something that you could tune to sub players at X % fatigue.
If they used a system like that, it would be cool for each head coach to have his own %s so you could see one, two, and even 3 RB systems and other various styles of substitutions.