I don't know about the Pats being the 2nd best team, or putting much stock in the way they beat Arizona. I loved what the Pats accomplished this year and it was a fun year, but they didn't play particularly well against the better teams. They manhandled some weak teams down the stretch to get to 11-5.
Clearly Arizona stepped it down a notch once they clinched, and have since ratcheted it back up. I think the Cardinals came into Foxboro against a Pats team that needed a win, got in some really crappy weather, fell behind early and said "thanks but no thanks".
It would have been fun to see how the Pats performed with Cassel and company, but I think the best team is representing the AFC in the Super Bowl.