Seems like a great deal for KC, especially as they got two players one of which is a good QB. NE I think should've been able to get better value, but the whole story as to why they settled for this is unclear, factoring in the KC GM connection. In addition, it has to be considered that KC's 2nd pick is fairly high. The fact that Brady is not yet proven as a sure thing to last another season makes letting Cassel go questionable, but they might have had to do it and/or had some good replacement drafts in mind.
The compensation is surprising, because two years ago, the Atlanta Falcons got two second-round picks from Houston for a far less experienced quarterback, Matt Schaub.
Bill Belichick either didn't get a better offer, or he did one of his best friends, Pioli, a favor with a player Belichick wanted to put in a good situation; Belichick is very fond of Cassel. It would not be surprising to see Belichick make the deal with Pioli because both were trained under Bill Parcells, and Parcells always made sure he watched out for his lieutenants and helped them whenever it didn't hurt him.