BOSTON (CBS) — Amid all of the pomp, circumstance, hype and excitement for Sunday night’s game featuring Tom Brady’s return to New England, there is this one unanswered question: Why isn’t Tom Brady still playing for the Patriots?

While the quarterback’s departure took place 18 months ago, its significance is still felt across the NFL. Brady went ahead and won a Super Bowl and a Super Bowl MVP with the Buccaneers, who hadn’t won a single playoff game in the 17 years prior to his arrival. Meanwhile the Patriots went through a 7-9 season without Brady, and they now sit at 1-2 heading into this game against the defending champs.

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Author Seth Wickersham, whose book “It’s Better To Be Feared” will be publicly available on Oct. 12, joined Breana Pitts and Michael Hurley on CBSN and helped answer the question of why Brady’s no longer in New England. As it turns out, the answer is rather simple.

“I think that if, after the Falcons Super Bowl [in February 2017], they had just signed Tom Brady to a five-year contract, so much acrimony could be averted,” Wickersham said on CBSN.

Brady, though, didn’t get a new deal in the offseason. And after winning the league MVP at age 40 in 2017 and setting a Super Bowl record with 505 passing yards in a losing effort to Philadelphia, he was only given essentially a one-year deal worth $15 million, plus $5 million in performance incentives, of which he earned none.

With Brady publicly expressing his desire to play at least until age 45, and with the Patriots going year-to-year with their quarterback, the situation was not built to last long.

“At the end of the day, I think that from the time that New England beat Atlanta in the Super Bowl, things just changed in the building,” Wickersham said. “And Tom wanted a contract that would — you know, they had just accomplished history, five Super Bowls together, and Tom wanted a contract that would take him into his stated goal of playing until he was in his mid-40s. And the Patriots were just resistant to do that.”

He continued: “Tom Brady had said, ‘I want to retire as a Patriot.’ Robert Kraft had said, ‘I want him to retire as a Patriot.’ And they were just never able to come to terms with it. And in August of 2019, it really came to a head, and Tom Brady considered walking out of camp in protest because contract negotiations were going so poorly. He ends up signing what was announced as a two-year deal but was really a one-year deal with an out at the end of the [2019] season.”

Wickersham said that as soon as that deal was agreed upon in the summer of 2019, Brady knew that his tenure in New England would be ending at the end of that season.

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“And as he said publicly, he knew that his time in New England was done,” Wickersham said. “Within a day of that contract extension, he and Gisele Bundchen put their house here in Boston up for sale, and I think that that more than anything kind of signaled what he knew privately, and that was that 2019 was going to be his last year in New England.”

While the relationship did, of course, end, it also lasted for 20 years, with an unprecedented run of six Super Bowl wins and nine AFC championships along the way. For that, Wickersham said, owner Robert Kraft deserves credit.

“I think that that’s where Robert Kraft comes in a little bit — I think that he did a phenomenal job, and he’ll probably get into the Hall of Fame because of this, because he was able to keep the band together,” Wickersham said. “And it doesn’t mean it didn’t come without challenges at the times, managerial challenges.”

Wickersham shared the story that was released in excerpt form earlier this week, in which Kraft expressed some disappointment in having to leave a conference in order to have to deal with Belichick — for whom the owner did not have very nice words.

“Generally speaking, even if these guys got on each other’s nerves, they realized that they needed each other to win football games, which is the most important thing to them,” Wickersham said. “Until finally, Tom Brady decided that it was time for him to leave.”

While the relationship — like any relationship — had its ups and downs, it was that pursuit of winning that kept the Brady-Belichick duo together for so long.

“What I write about in the book is how these two men — Tom Brady and Bill Belichick — achieved the greatness that they did and what the costs of that were,” Wickersham said. “And it’s really something that I just spent a lot of time on, just trying to figure out what were the keys to their greatness.”

It’s all in the past, but Brady’s return this week certainly drudges up a lot of emotions and opinions in New England. And while Brady has gone on to thrive with his new team, Wickersham drove home the idea that this reality could have been avoided if the Patriots had just committed to Brady through his early 40s.

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“I do think the contract was the biggest thing,” he said. Staff