You know how when you flip a run on offense your QB pats his leg and says something and it gives it away? Well, I'm sure most of you know that you can fake flip the run by flicking the R-Stick to the side that the run is already on (your QB will do the same animation). Well in practice mode I came across a way to flip the run without the animation happening at all (I've yet to see if it works in games, it should). If you press X (on 360, I think it's square on ps3) to open up your audibles, and then you press B (circle on ps3) to cancel, you should be able to flip the run after that without any hints by the QB. Not sure if people know about this or not but I thought I'd post it anyway.
NOTE: This is for flipping the direction of the run with the R-Stick, not flipping the actual formation and play itself.