"So let me see if I got this straight," Allen wrote in his new autobiography, per Sean Deveney of Sporting News. "You want to pay me less money. You want to bring me off the bench. You want to continue to run the offense around [Rajon] Rondo. Now tell me again exactly why I would want to sign this contract?"
Allen said he was seeking a three-year, $24 million contract whereas the Celtics were offering a two-year, $12 million pact. He ultimately chose to sign a two-year, $6 million deal with the Miami Heat, choosing his best chance for a title rather than staying in Boston.
"I knew fans in New England wouldn't be happy with my decision," Allen wrote, "but I never could have imagined the degree of unhappiness. They acted as if I was Benedict Arnold. ... My sin was that I had the nerve to leave on my own."
Allen's decision ultimately proved correct. He won another championship with the Heat in 2013, hitting perhaps the best shot of his entire career in Game 6 of the NBA Finals. The Celtics, meanwhile, struggled after he left and ultimately disbanded their team in 2014, shipping Paul Pierce and Kevin Garnett to the Brooklyn Nets.
Allen's relationship with Garnett is still yet to recover, while he and Pierce have made amends. Rajon Rondo and Allen, whose tense relationship receives some focus in the book, has also never recovered.
"KG would quarrel with his grandmother if she signed with another team," Allen wrote of Garnett.
Allen has not played since the end of the 2013-14 season. Pierce and Garnett bounced around a bit at the end of their careers, with Pierce suiting up for the Washington Wizards, Los Angeles Clippers and Nets while Garnett played in Brooklyn before being traded back to the Minnesota Timberwolves.