Hear me out... I would say that the years that prove that Brady is the greatest ever are not the years they won super bowls. when you win a Super Bowl you usually have a dominant or at least great defense. the Patriots are no exception to that. In those years a pretty good to very good quarterback could be expected to help put his team in position to win a Super Bowl, and make clutch plays and Brady did with all of those teams that won. but there were years that their defense was absolute ass and Tom Brady was the biggest player reason why any of those teams got to where they did in the playoffs. I think his greatness is more defined by having a lesser team around him and/or a decimated coaching staff around him and still doing yeoman's work to help get the team where it was.
I've long said that elsewhere that his 2005 and 2011 seasons should have been considered for league MVP. reason being that 05 defense was absolute trash for a majority of the season and it was the offense led by him that helped the Patriots win a bunch of games on the way to the divisional round. granted the defense had gotten into pretty good shape by the end of the year but they wouldn't have even been there if it wasn't for his performances on offense. The 2011 defense was just trash the entire year and never got better and I believe to this day is still the single worst defense ever to reach the Super Bowl. Honorable mention for one of his great not great years was in 2015. the culmination of that season against the Denver Broncos was the singular most courageous performance I have ever seen by Brady. yes they lost, but he just kept going. Despite the injury decimated roster, and the loss of Scar heavily impacting the ol, he kept getting up. he was getting his ass beat to an absolute pulp and he just kept getting up and rallying the team and they damn near made it. And that Broncos team rode an amazing defense to a Super Bowl win that year.
Years like those are the ones that defined his greatness to me. they showed what he was that separated him from any other quarterback I ever saw play.