Statistics are like prisoners - they'll tell you whatever you want if you torture them enough.
Pre-salary cap, the NFL had super teams that stayed together. Best GM was the guy with the fattest checkbook; best coach was the guy with the best GM.
Look at the Steelers Superbowl rosters - pretty much the same team. Same with the Dolphins in their glory days.
Shula had the best QB in the league for years and never won it with him.
Bill is certainly in the conversation, along with one or two others.
EDIT: And let me add...game planning beat the Rams in 2001. Faulk was shocked by McGinnest.
BB was also the only coach who figured out how to shut down Peyton Manning, year after year - if BB was coaching the Colts at the turn of the century, they would have had a dynasty. Nobody shut down those Colts except the Patriots. They rolled up the score on everyone, except the Patriots.
BB is the only coach who would have goaded Carroll in those last critical seconds, and he had worked the team all week on the very play that got Butler the chance. Everyone thought he was making a mistake in not calling a time-out.
Defense beat the Rams.
Preparation for a long halftime played a huge role in beating the Falcons.
He won a Superbowl without a secondary made of band-aids.
All that stuff matters...tiny details (Brady just talked about the preparation) made the difference. I was at the Superbowl after-party following the game where Chatham clobbered the streaker. He was asked if he was shocked to see that guy running down the field. He answered something like "Nah, I play for Belichick. We watched film of that guy all week." (I hope I'm remembering this right). That's a joke, sure, but it speaks to what Belichick was all about. Details, putting in the work, sacrificing for the littlest of edges that might make a difference. That was Brady, too, which is why they worked so brilliantly together,and it's why the Pats won several Superbowls where they didn't have the best roster.
Taking those things for granted isn't remotely fair. New England fans should celebrate the guy (both guys), not attack him, but alas, we live in Felger's world now.