As I see it, the Pats strategy of lobbing the ball down the field is not as dependent on the QB as we thought it was. Sure, they've had to make a few adjustments for Cassell, but now that he "gets it," you can see that the attack is a quick throw down the field to a spot, and it makes the corners play good coverage. Because the line can hold a block for a couple of seconds, and the Pats often go shotgun, the only recourse is to blitz, which makes this even more effective.
Anyway, the Pats are running the modern day version of the run-and-shoot, which few teams have the personnel or scheme to defend. And now that Cassell is comfortable, some teams (like Miami) will struggle with it.