Brady is a great QB, but I think that Bill Belichick was overall more important to the success of the Patriots franchise. The guy just has an eye for detail that most head coaches lack. Another poster said it best, he's a coach that would coach his coaches. His approach to the game is just different than most head coaches in the NFL. Most guys are like Carroll or perhaps Reid, they stick to their respective schematic philosophies and don't deviate. Belichick on the other hand will pull out some formations that others have never seen him use. One season he may be 4-3 the next he may be 3-4. Sometimes he'll be a smashmouth, hard-nosed football team, the other times he'll field an Andy Reid style finesse offense. His adaptability and willingness to change his schematic philosophies on offense and defense at a moments notice is something I haven't seen from many head coaches.
Most coaches just learn one style from another coach and it becomes their identity. Reid learned from Holmgren, he has stayed current with trends, but the WCO is still very apparent in his approach. Carroll was a disciple of Monte Kiffin, and and as a result we see many of the same concepts. He's changed up a few things for sure, but you can clearly trace the lineage. They've added things here and there but it is very clear what the genesis of their philosophies are. Same could be said about most of the coaches in the NFL. How Bill Belichick operates is very far away from the Parcells system he was brought up in. Occasionally he returns, but he has flirted with many different approaches and systems. He is a chameleon that changes with the scape of his team and his opponents. I can't say i've seen many coaches in the NFL operate the way Belichick has. They are too married to their way even when the team situation doesn't necessarily merritt that particular approach.
I think Brady would still be an elite QB, but I think he would have just one or two rings without Belichick assuming that he had the same skill level throughout his career. I think that if you put Wilson, Brees, Rodgers, Peyton Manning, and a few others on the Patriots that you would get similar results.
