I don't really enjoying being on defence to be honest. I'm not one of the guys who audibles on D, knows the hacks/formations to get instant pressure etc... or user controls an outfield player. I just tend to control a Dline-man and try to initiate a block shed for pressure/sacks. At the end of the day if the AI wants to make a play it'll make a play regardless of what I do (without cheesing). I try, and I try to learn - but they'll score/break a tackle/beat a press everytime they want to. Especially in the final 2 minutes of the half/game.
I will occasionally switch from a blitz to a cover 3 or Tampa if I see a complete mismatch in the line-up (i.e. 5 wide shotgun formation by the oppo), but generally I rock with zone blitzes.