Instead of playing the flats from the snap, I'd try to find a delayed flat cvg. scheme. I wouldn't be worried about giving up the flats as much as rallying to the ball once it's caught in the flats. Let them get 30 catches in the flats but as long as they are not getting yac. eventually they'll go to another area of the field, and then the chess match begins.
I'm wondering if after the ball is in the air you could press down on the right-stick, like your playing the run but instead the defense reacts to where the ball is and swarms to tackle.
See these tactics have been used by online Madden gamers since it was introduced, it's just a matter of figuring out what stops it and forcing them out of their comfort zone. I'm not online playing anymore but I know theres usually a counter to stuff like this.