Rumor is that Belichick had a falling out with Kraft after the Spygate fiasco but Kraft couldn't fire Belichick at the time because Goodell convinced Kraft that it would hurt the NFL and even more so the Patriots. Firing Belichick would only add to the flame the idea that the video taping was a big part in our SB seasons. So Kraft has been stuck with Belichick, more or less. What makes it even more interesting is that since then, Belichick has been planning to move his operation out west, where he doesn't see as big a competition as he does here (since Parcells was hired in MIA). He apparently consulted the Hunts to hire Pioli and the Hunts agreed with the caveat that Belichick himself would come later on
(this part is pretty unbelievable IMO). Belichick then traded Cassel and Vrabel to KC for a mere second round draft pick when he was offered a lot more from other teams. Apparently, BB was sold on Cassel after the 08 season that he could win a SB with a good team around him and placed him in KC to be his QB once he gets there. Vrabel was sent for his leadership and because he's BB's most effective enforcer. This was supposed to be a 3 year plan, with BB finally leaving the Pats after the 2010 season, but after Weiss and Crennel both became unemployed, it became obvious that it's time to pack up from NE, hire Weiss and Crennel, and see if they could rekindle what they had here in NE earlier this decade in KC.
Take it for what it's worth, it could be a useless rumor...