I feel ya man, this is just one of those issues that has always been a problem since the beginning of Madden, teams that consistently run the ball and overpower teams every sunday, should do the same thing on Madden, the cpu should know the strenths and weaknesses of every team and use them accordingly, IMO its common sense.
Know that I'm done with my rant, here is my advice and the only thing that will force the cpu the run more, turn all of the rush defense sliders to 0, u will give up a big run once in awhile and it will be challenging to stop the run, but the cpu should run successfully which tends to force the cpu the commit to it alot more. Hope this helps..