Anyone know how defenses are simulated?

[raguel]

I'm currently playing as the Browns in my franchise. I switched them to a 3-4. My defense overall at this point is pretty good but in simulating games it's giving up ~25 pts/game. Now I suppose I can understand that if my defense is being sim'ed as a 4-3 (mediocre second tackle and OLBs are in coverage and not pass rushing) but I don't know if that's true or not.