A new book by Seth Wickersham called "It's Better To Be Feared" revealed the inner workings of the New England Patriots that dominated the NFL from 2001 to 2019. The book specifically illuminates the power dynamics between Robert Kraft, Bill Belichick and Tom Brady. 

Wickersham writes that Brady ultimately left New England not only because both Belichick and Kraft refused to commit to him until his stated goal of playing until age 45, but also because he wanted to be with a franchise that welcomed his input. 

"Tom Brady had been curious if there was another way of winning, and while nobody was arguing that Bruce Arians was a better coach than Bill Belichick, or even close, the seamlessness of Brady's proficiency and performance was making his former coach's methodologies look antiquated, even silly," the book says. "It was better to be feared -- but was it necessary?"

As examples of what the dynasty wrought, Wickersham writes that Kraft once called Belichick the "biggest f----ng a--hole in my life."

In 2018, the trio were trying to set aside grievances in order to remain victorious. 

"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 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.

"As for Kraft, in late September, he was in Aspen [Colorado] for a conference and bumped into a few friends in the hotel lobby early one morning. He told them he was leaving later for Detroit, where the Patriots were playing their next game. 'I hate leaving here,' Kraft said. 'You leave here and you leave some of the most brilliant people you've ever met. You pick up so much knowledge from all these brilliant minds. And I have to go to Detroit to be with the biggest f-----ng a--hole in my life -- my head coach.' "

"Bill was an idiot savant," Kraft told a confidant, according to the book, alluding to Belichick's reputation before he hired the former Cleveland Browns coach in 2000. "I gave him this opportunity."