Works better against humans. Start the game with an onside kick. If you get it... AWESOME! If not, oh well... you have bad field position. But the NEXT time you kick the ball, chances are your opponent might prepare by setting up in an onside kick recovery.
Madden 13 Tips: Onside Kick Tutorial - YouTube
If they do, and you squib the ball, you're in good shape. Aim to the far left and kick the ball at about 25% power. You'll get the ball back almost 100% of the time.