As a Steeler fan I am one of the last people who would defend Belichick, and I don't really think that I am that much but, saying that a coach isn't as good when he doesn't have one of the greatest players of all time on his team seems kind of silly, of course any coach is going to be more successful when he has great players
Chuck Noll won 4 SB in 6 yrs, and then was pretty mediocre thru most of the 80's, was he a great coach or did Bradshaw, Harris, Swann, Stallworth, Webster, Greene, Lambert, Ham, Blount, and others have something to do with it?
Glen Sather won a bunch of Stanley Cups when he had Gretzky and Messier, and all the other stars, did he forget how to coach when those guys were no longer on the roster?
Joe Torre won 6 pennants and 4 WS with the Yankees and had a .605 win % and 406 games over .500, yet the other 4 places he managed he won nothing and is a combined 77 games under .500, I wonder what the big difference was?
Shula was very successful, and he still has the only undefeated season, which is an amazing accomplishment, but if anything I kind of feel like he was an underachiever, he only won 3 of 6 SB appearances with Miami and presided over the biggest SB upset loss with the Colts. Also had Dan Marino for all those years and could only get to 1 SB which they got throttled in, and had a career playoff record of 19-17, he had 9 years of one and done in the playoffs and missed the playoffs 11 times in the SB era
I hate Belichick as much as the next guy but his accomplishments speak for themselves, he even won a playoff game with the Browns. Maybe it isn't ending great for him, but he won't be the first one who might have stuck around a year or two too long