2. Thoughts on Brady's departure: What are the primary factors that led Brady to this outcome? My thoughts:
One of the things Brady relayed to some close to him was that he felt he had squeezed everything out of his partnership with Belichick after 20 years. So from his standpoint, it was time, unless there was a fundamental shift after two challenging contract negotiations in 2018 and 2019.
That shift never came. Had Belichick decisively approached Brady with the clear-cut thought of, "I'd like to make this work so you can finish your career here; let's try to hammer this out," I believe there was a chance it could have continued. But I don't think Brady expected that was ever going to happen -- that's not Belichick's way -- which is why Brady had mentally prepared himself to play elsewhere in 2020.
Why wouldn't Belichick do that? Only he has the answer, which is the way many things are with his close-to-the-vest management approach. Perhaps he ultimately thought that he, too, had squeezed everything possible out of his partnership with Brady. Or maybe he thought Brady would never leave, or at the least give the Patriots a chance to "compete" with what teams were offering him on the market.
Part of it is the strategy with which the Patriots generally negotiate in which they withhold any offers as players are allowed to test the market while still keeping an open dialogue with them. That is one way the Patriots avoid insulting a player with a contract offer. It also protects them from the player taking an offer to another team as a leverage play. So, my understanding is that Belichick and Brady never had meaningful contracts talks since last August; instead it was like a dance to see who would make the first move.
That highlights the overall dynamic of the situation to me, ever since the Patriots agreed not to place the franchise tag on Brady last August: For this to work for a 21st season, Brady and Belichick had to want each other, and owner Robert Kraft wasn't going to force the marriage. I thought Brady and Belichick would eventually get to that point, ultimately coming to the realization that being together was best for both of them. But, it never unfolded that way.