BOSTON (CBS) — We knew that the relationship between Tom Brady and Bill Belichick was pretty bad leading up to the quarterback’s departure for Tampa Bay. But we’re now getting details of just how bad it was between two of the figureheads of the New England Patriots.

Excerpts from the book “It’s Better To Be Feared” by ESPN senior writer Seth Wickersham have been released ahead of Sunday’s Patriots-Buccaneers game at Gillette Stadium, and it makes it sound like it was a small miracle that the Brady-Belichick relationship lasted until 2019.

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Brady left the Patriots after two decades of NFL dominance because Belichick and team owner Robert Kraft weren’t committed to the quarterback playing through the age of 45. Brady also wanted to play for an organization that listened to his input, and in New England, he felt ignored when he would share his thoughts on how the team should use all the money it saved when the quarterback continued to sign team-friendly deals.

“Brady was tired of taking team-friendly deals with no input into how the money saved was spent — and still wanted a long-term contractual commitment,” Wickersham writes.

Belichick also had his own feelings of distrust.

“Belichick told associates that every organizational decision now was in support of Brady, geared toward pleasing him and making him successful — and that Kraft meddled with the team, sometimes with opinions, sometimes with restrictive budgets,” via Wickersham.

As it turns out, Kraft was also none too pleased with Belichick in the final years of Brady’s tenure in New England.

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“Kraft sometimes groaned to confidants that Belichick didn’t show him the respect he deserved, but he was in no rush for life after him,” Wickersham writes. “Brady, though, seemed ready for it. … ‘I don’t want to play for Bill anymore,’ he told people close to him in 2017.”

During the 2018 season, Kraft called Belichick the “biggest f—-ng a–hole in my life,” according to Wickersham. The owner also told a confidant that “Bill was an idiot savant” and that he had given the head coach “this opportunity” to succeed in New England after he failed as a head coach in Cleveland.

As the situation was reaching its peak, Kraft, Brady others even discussed scenarios of replacing Belichick. Offensive coordinator Josh McDaniels was the prime candidate, but with fears that he would leave for a different head coaching opportunity, former offensive coordinator and then-Houston Texans head coach Bill O’Brien was also discussed.

O’Brien was in a power struggle with the Texans at the time, and was actually trying to get fired so he would be in line for Belichick’s job. But the Texans chose to go with O’Brien over GM Rick Smith, which ended his chances of taking over the Patriots.

Despite all the turmoil between Brady, Belichick and Kraft during the 2018 season, the Patriots still went out the franchise’s sixth Super Bowl title to close the season.

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Wickersham’s book provides several other juicy details on the inner workings of the Patriots and their place in the NFL, and makes it clear that it was not all sunshine and lollipops despite all the franchise’s success. Based on the excerpts released Wednesday, Bill Belichick’s PR is going to take a massive hit when the book is released on Oct. 12.

CBSBoston.com Staff