It pretty much turns the defense psychic when it's on. For example, one play had me running a run stretch to the left, and a CB blizted from the left and immediately blew me up in the backfield. When it showed the play the defense ran on the next playcall screen, the unflipped playcall was supposed to have the CB blitzing from the right. So basically as soon as I picked my run play, they knew exactly where I was running, and autoflipped to it.
Turn that stuff off, and you have a much more fair game, and probably more success on the ground without the defense auto adjusting to where you're running.