This is so misleading. Belichick didn't have the best career in Cleveland, but he did turn around a bad team into an 11-5 playoff team only to have the owner totally sandbag him the following year by announcing the team was being moved out of Cleveland to Baltimore. I don't think Belichick was a great coach then, but he wasn't nearly as bad as his detractors made it,
When he came to the Patriots, he inherited a bad team that didn't fit his system and turned it around into a Super Bowl champion the second year. Sure Brady was the QB most of the season that year, but he was mostly a game manager and the Pats won on defense. They won the Super Bowl, not because the 13 points they got on offense, but because they shut down the greatest show on turf.
And Belichick was 11-5 with Matt Cassell as QB when Brady went down.
With the Patriots, Belichick has only coached three seasons without Brady. Two of those years were rebuilding years. One they went 11-5 and only missed the playoffs because of a fluke.
To say Belichick has sucked without Brady is a very superficial analysis only looking at the wins and losses. And even looking at TDs doesn't make sense since six of the eight years that Belichick coached without Brady were before the NFL offensive explosion where defenses could actually play defense.