Agree with all the previous posts, home field advantage is huge, Larry Fitzgerald is playing this time, running game is improved and so is the O-line.
The coaches have had extra time to prepare and the team gets an extra practice or two. Outside of Drew Stanton, the team enters the game 'relatively' healthy, especially if the Honey Badger plays, which I expect.
Also, Chandler Catanzara seems to have recovered his confidence and in a close defensive struggle that could be decided by a field goal, that is huge.
I believe the key to the game will be the Cardinal offensive line. Seattle can be run on up the middle. If the Cardinals have SOME success, as the Niners did early, before their top two backs got hurt, it will help immensely. Jamal Charles averaged 8 yards per carry against the Hawks. Yes, I realize the Hawks didn't have Bobby Wagner and the Cardinals don't have anybody close to Charles in ability. But IF they can have SOME success on the ground, they 'shock the world' again on Sunday night.
Remember almost nobody thought the Kurt Warner Cardinals could beat Philly in that NFC Championship game.