I think I'm saying more that I feel like people are probably mis-evalutating talent, and like shady said, I think that may be OK. Knowing every aspect of the game would make it pretty boring. I think when people say their QB,RB,WR,TE,OL,DL,LB,DB are better, they look at the 2-3 things they think matter most, forget about the rest, forget about IQ, forget about the situation into which they put their players.
I'm betting that when people go up against SIMs they still just use their default or "vs SIM" gameplan and don't put the same effort in as when they play a human coached team. I know that there have been plenty of times I've overthought an opponent and changed my plan when I shouldn't have. SIMs don't do that. SIMs put a lot of time into team practice and I gather most people are all about individual development.