By Matt Audilet Bruce Arians’ sudden retirement as head coach of the Tampa Bay Buccaneers caused an immediate whirlwind of speculation around the league. Did Tom Brady’s return have anything to do with his departure? Or was it simply just a sudden change of heart? NFL Network insider Ian Rapoport believes he has the answer to the awkward timing of Arians’ retirement. He feels the Super Bowl-winning head coach was just making sure things were in order before handing the keys over to his friend Todd Bowles. “What it sounded like he wanted was everyone to re-sign and everything to be settled befo…