Earlier this week, a former NFL defensive player explained part of the reason that Bill Bellicheat couldn't defend the Wildcat. What it boils down to is that no NFL defense ever accounts for the QB in their scheme. And splitting a QB wide on the top corner causes mass confusion for the defense.
For those of you who wonder what I'm talking about, allow me to explain: While the offense lines up 11 players, there are only 10 who are involved in a running play in most cases. The 11th is the QB. His job is to receive the snap and hand it off, then "get out of the way"...so the defense is using 11 guys to try and stop 10. In those relatively rare cases where a QB is involved further in a running play, it makes the hilight reel, because they're throwing their bodies to block someone - and that's unusual - or its some kind of a trick play.
But let me add that during most passing plays it is 11-11, because the QB is actually throwing the ball. Only when he lines up wide and someone else takes the snap, do we have a similar situation to the running play.
So by putting a running back "under center" (he was in the shotgun), you now have a different threat. The QB splits out wide and the CB has to cover him. Now in most cases last week, they put Pennington on Ellis Hobbs. One thing the Dolphins apparently noticed was that the Pats only have two true corners on their roster, and its all about scheme with them. So, on most defensive plays its their better corner (Hobbs) and Deltha O'Neal who is 32 years old, and has been cut by several teams in recent years, lined up to take on the receivers.
When the play starts, Pennington has to be covered. Now, he's no threat really, to catch the ball. But, he makes Hobbs cover him. All Pennington had to do was jog a little upfield - away from the play - and take Hobbs out of the play. Now, you've got 10 on 10, with Brown being able to see the defense from his position and start running right away.
And because he had no other corners, Bellicheat was stuck.
The other part to this play was that the Phins attacked the very good Patriots defensive line at the point of attack, and took out the younger linebackers with offensive linemen. That left the rest of the actors - Williams, Martin, Hagen - to either distract the slower, older players or chip them and let Brown use some speed to rush through and make a good gain.