What Bill Bellichick has done is why HE's the GOAT. There have been a lot of HC's who have had great years and even great runs. But he's in VERY rare company when it comes to MAINTAINING excellence over a long period of time. And he's ALONE in doing it for a long period of time under the strict salary cap rules of the last 30 or so years.
Look at all the HCs/GM's who constantly get wide recognition when their teams do well. Win a championship, or go to a superbowl, and have a stretch of a few good years. But then inevidably they have a down year or two. The Harbaugh Brothers are great examples, and one of them lost his job because of it. Parcells is another example. He got into the HOF for taking multiple teams to the superbowl. A great achevement, but he was a builder and NOT a maintainer. Parcells had a 4 or 5 year shelf life before his players stopped listening to him, and his greatest skill was he knew it.
MAINTAINING greatness on a team is MUCH more difficult than building a great team. To do that you need a great GM, and for all the so called misses he makes in the 2nd round, he'a made enough hits to rebuild his roster at least 3 times during this run. The guy in Baltimore whose name escape me is universally acknowledged as being the best GM in the league has watched HIS team sink into rank mediocrity for several seasons over the years.
BB is the best HC in the league almost EVERY year, but has only won the award a couple of time over this run. BB the GM has had several years where he deserved the award over the years, yet, to my knowledge, has been rare even mentioned, let alone won the award.
But I guess the good thing is, in BB's priority list of things he wants to win, the HC of the year and the GM of the year is likely at the very bottom of that list....at least in triple digits in importance.