No team has perfect execution. All that matters is the final score.
The Patriots missed two field goals and threw an end zone interception in SB38 and still won. Did they not deserve to win that game?
There's two teams out there at all times, both capable of forcing the other team to make errors, both capable of making errors themselves.
Super Bowl opponents are fairly evenly matched on the whole, yesterdays game was supposed to be a mismatch and i doubt so much as one Patriot fan picked the Cards to win. I don't think the Patriots came even close to playing their best football and they made numerous critical mistakes that allowed Arizona to come into Foxboro and walk out with a win. If you simply want to go by the final score you are obviously welcome to look at it that way but I think expectations play a role in how games are perceived and the Patriots were clearly considered a much better team playing at home against a team that doesn't win on the east coast, and their mistakes played a big role in the loss.