The league, including Belichick, is pretty archaic in its thinking. Belichick is the most advanced caveman of the bunch.
For instance, the league still likes to 'script the first 15 plays of the game' and get a feel for the opponent. But, teams that are leading by 8+ points in the first quarter have traditionally gone on to win 80% of the time.
So, what does Belichick do? He has a very aggressive offense that doesn't script the first 15 plays and tries to score. Meanwhile, his defense uses a lot of bracket coverage deep and gives away the short stuff. Why? Because teams usually go deep in the first half. When the game become close in the second half, they are more likely to play it safe.
He's also the best coach of safeties in the world. That last line of defense is important. According to former NFL Safety Matt Bowen, the safety position is the worst coached position in the NFL. And here you have a coach that is the very best at doing it. This helps create a defense that may not always dominate, but usually shows up week in and week out and is tough to score on because they don't blow assignments and give up big plays.
It also helps to have Brady. But to Belichick's credit, he was willing to change his offense to suit Brady's strengths. Charlie Weiss' offense was more of a 2 TE, run the ball and play action type. The numbers have shown that Brady isn't all that good on play action. They then went to this hyper passing offense that constantly uses the shotgun. Back in 2007, that was a very radical idea. They also spent a 2nd round pick on Wes Welker who greatly changed the passing game in the NFL. All under a very young O-Coordinator in Josh McDaniels. But, this played to Brady's strengths which is the underneath routes and out patterns, instead of the deep fades and seam routes.
Lastly, he plays in the worst division in football over the past 15 years. Life is a lot easier when you have the Jets, Bills and Dolphins and the mess they have been over the past 15 years. It's a lot easier to win a division and get HFA when the best QB that those teams can muster in the past 15 years is Chad Pennington. And when the best HC they could muster was Dave Wannstedt.
Not only does it make it more likely to lose those games, but when you have formidable opponents in your division it means better gameplanning and scouting, exposing weaknesses, etc.
I'm not the biggest Andy Reid fan, but he's a solid HC and a very good gameplanner and great at exposing weaknesses. Do I think he's a better coach than Belichick? No. But, I think if Reid was in the AFC East the Pats wouldn't run away with the division so often and he can expose weaknesses in the Patriots that other teams can learn from and exploit.
If anything, i think Belichick has a very keen understanding of the psychology of the NFL and how coaches and execs think. How they become desperate, how they don't want to deviate from the norm because it's 'too risky' when in reality it's less risky than doing what they have always done. He understands the archaic and backwards thinking of the NFL and takes full advantage of it.
YR