Since Peyton Manning has come into the league the Indianapolis Colts have made a living off of play action passes. Manning uses the play fake better than anyone else to strategically move the linebackers out of position and create holes in the defense to throw to. Tight end Dallas Clark benefits the most from the run game and play fakes. The play action is so effective because the run play and the pass predicated off of the same play are almost indistinguishable from the snap until the time Manning pulls the ball back to throw.
Here is a play action series the Colts use all the time. The Colts love to run an inside read play. This means the O-line will kick out the defensive ends, and combo block the defensive tackles and linebackers, the back gets the hand off, finds the hole, then makes a cut and gets up field.
The second play is the play action pass off of the zone read play; notice how similar the blocking assignments look. This is a max protection scheme where the tight end and back stay in to block. When the ball is snapped the defense believes they are simply seeing the same zone read play out of a flipped formation. The linebackers read this and attack the line of scrimmage. When Manning pulls the ball back the linebacker has vacated his zone in the standard cover 2 defense. The safeties will both go with the outside receivers because they have deep coverage responsibilities, as soon as Manning gets the ball ready and Dallas Clark (the slot receiver on the left side) clears the linebacker, Manning will hit him right in the seem of the coverage (red circle), typically resulting in a big gain.
The Colts also like to use the play action in goal line or short yardage situations because the defense anticipates, and sets up to stop, the run. Below is a goal line play the Colts use when Manning sees the defense committing to the run.
Here the linebackers and strong safety are going to attack the run and vacate their pass responsibilities. Anticipating this, the Colts had called a play action in the huddle. The Colts are only going to send 2 receivers into routes on this play and leave the rest to block because the play action takes a little longer to develop, and the defense has 11 players attacking the line of scrimmage. Clark (the tight end) is going to release like he is trying to block the linebacker, as the linebacker fights past him and toward the line Clark will get to the back of the end zone, behind everyone else, and the work to the outside, away from the defenders.
The play action pass can be an outstanding offensive tool. If the run game is going well holes in the secondary will be greatly exaggerated and will be easy for the offense to exploit. A decent run game, and good play action game, will give the defense a catch-22 that can be almost impossible to handle.