How do you do bump and run coverage on Madden 2010 for the ps3?

I have been trying to figure out how to do the bump and run coverage on madden. I thought what you were supposed to do was either choose a play that says "press" after the play name such as cover 1 press. Or i thought you could just press triangle then press down. I am playing with the Packers and sometimes Al Harris goes and he does jam / block them at the line for like 5 secs, however 9 of 10 times he starts moving towards the raises his left hand then just runs with the WR. I was wondering if im doing something wrong or if madden 2010 has a flaw in the game.