Why did Tom Brady leave the Patriots? A souring relationship with Bill Belichick and other signs from the past

By leaving the Patriots, Tom Bradyending a partnership between the greatest quarterback of all time and the greatest NFL coach of all time,breaking up the most powerful dynasty the league has ever seen.

The shocking nature of Brady's departure from New England after 20 years makes it easy to forget the seeds for this move were planted long ago.

MORE TOM BRADY:
O​ther Hall of Fame QBs who changed teams

The reason Brady hit free agency at age 42 was notbecause New England failed or refused to extend his contract. His first trip to the open NFL market was a deliberate effort on the part of the quarterback. When Brady restructured his contract with the Patriots last summer, he might not have known at the time he wanted to leave. But he knew he at least wanted the option.

Brady's extension, completed in August, gave New England an additional $5.5 million in cap space for 2019. That was the only positive for the Patriots. The deal included a provision that stated the team could notfranchise or transition tag the QB in 2020. And while the contract included two additional years beyond 2019, those years would automatically void on the last day of the league year.

The last day of the league year was Tuesday, the same day Brady informed the world he would play out the rest of his Hall of Fame career somewhere other than New England.

Brady's departure left a $13.5 million dead cap hit on New England's books for 2020. Reports indicated the Patriots were hoping to avoid that charge and convince Brady to return after testing free agency. According to the Boston Globe, New England "gave Tom a number. He didn't want it." According to NBC Sports Boston, though, "a tangible effort by the Patriots to keep Tom Brady in New England never happened. No negotiation. Just the intimation that it was on Brady to say what he wanted. For Brady, that stance spoke volumes."

New England's approach — remember, his phone conversation with coach/general manager Bill Belichick a couple weeks ago reportedly did not go well and was strictly business — likely was the last straw for Brady.

But it clearly wasn't the only reason Brady wanted out. There was the restructured deal almost a year ago that allowed him to hit free agency. There was Brady putting his New England mansion up for sale (though he continuously downplayed the significance of that development).

MORE: Remembering Brady's final pass as a Patriot

Brewing in the background all along was the souring work relationship between Brady and Belichick. Many suspect the root of their rift was the Jimmy Garoppolo trade fiasco of 2017.

Belichick wanted Garoppolo, whom New England had picked in the second round of the 2014 NFL Draft, to replace Brady as the starting quarterback once the older passer was finished. Keep in mind Brady had just turned 40. According to ESPN, Belichick "repeatedly offered Garoppolo four-year contract extensions, in the $17 million to $18 million range annually that would go higher if and when he succeeded Brady. Garoppolo and (agent Don) Yee rejected the offers out of hand, for reasons that remain unclear, and the Patriots knew they couldn't make any promises to Garoppolo about the timing of a transition at quarterback without it getting back to Brady."

Team owner Robert Kraft reportedly was set on sticking with Brady as long as he wanted to start in New England, and Belichick was forced to play ball. From the ESPN article:

"Two weeks before the Nov. 1 trading deadline, Belichick met with Kraft to discuss the quarterback situation. According to staffers, the meeting ran long, lasting half the day and pushing back Belichick's other meetings. The office was buzzing. The meeting ended with a clear mandate to Belichick: trade Garoppolo because he would not be in the team's long-term plans, and then, once again, find the best quarterback in the draft and develop him. Belichick was furious and demoralized, according to friends. But in the end, he did what he asks of his players and coaches: He did his job."

According to the report, Belichick took "pride" in seeing Garoppolo succeed with the 49ers, and that he dealt the QB to a team he thought would allow Garoppolo to flourish. That would explain why San Francisco had to give up just a second-round draft pick in the deal.

There were other deep issues between Brady and Belichick. Later during the 2017 season, Belichick banned Brady's trainer Alex Guerrero (also a close friend and business partner) from the team's plane and sideline.

When that happened, another friend of Brady told ESPN, "Tom changed. ... That's where a lot of these problems started."

Brady and Belichick reportedly also differed on Belichick's no-nonsense coaching style. Former Patriots cornerback Aqib Talib thinks that ended up being a big reason Brady decided to leave.

"If (Belichick is) treating everybody the same in the meeting room, he's probably treating everybody the same around free agency time, as well,” Talib recently said on NFL Network. "I think Tom is gone. I think it’s a done deal, and Bill is going to be Bill. Them calls are going to be short and to the point.

"We got a report that said (their call) didn’t go well. I had a call that didn’t go well with Bill before, so I can imagine what happened on that call. It’s kind of a chip on both of their shoulders that’s like, ‘I want to do this thing and see if I could do it without him.'"

MORE: What if Mo Lewis never injured Drew Bledsoe?

That last point from Talib is important, because it might be the bottom line for Brady in his decision to leave New England. After all, even as the relationship between Brady and Belichick evidently deteriorated,and even as Brady aged into his early 40s on team-friendly contracts,the Patriots were winningdivision titles,AFC championships and a Super Bowl.

Brady, a hardcore competitor whose entire career has been fueled by the chip his 2000 NFL Draft slide left on his shoulder — his new content company is named 199 Productions because he was selected No. 199 overall — just gave the football world a new reason to doubt him. Yeah, he may be the greatest quarterback of all time, but can he succeed without the benefit of a roster constructed and coached by Belichick?

Everybody wants to know, and perhaps Brady is simply eager to provide the answer.