I know I'm not charter but I have also been running with default all-pro and have been getting great results. I find that the CPU run game is perfect and it all depends on what defensive plays you call. All-pro is perfect for me because I believe that it's enough of a challenge to make me think about what defensive plays I call. If I load the box to stop the run, I'll usually do just that. But if they CPU offense starts calling play fakes then I will get burned with a loaded box. So then it becomes a chess match and makes me use more strategy, which is the main reason I'm enjoying this game this year.
Also, don't be afraid to use the guess play feature before the snap. It really emphasizes more use of strategy.