The weekend's biggest upset goes under the Football Outsiders lens.
Though it's easy to blame Seattle's loss to St. Louis on trick plays and special teams, Andrew Healy says teams are starting to exploit weaknesses in the Seahawks defense.
How did Dallas knock off the defending Super Bowl champs? By shutting down Percy Harvin and getting the play of the year from Tony Romo.
The keys to New England's win over Cincinnati? A deep passing attack and a critical new weapon.
For several reasons, Sunday's upset in Pittsburgh looks more like a Steelers loss than a Buccaneers win.
San Francisco's loss to Arizona had less to do with Colin Kaepernick's performance and more to do with a key injury.
Why have Kenny Vaccaro and the Saints' secondary been such a headache for New Orleans this year?
This probably isn't the end for New England, but there are definite signs of concern. As for Miami, where did that offensive line performance come from?
San Francisco held off Arizona to claim the No. 5 seed by jumping on the Cardinals defense early and taking advantage of poor Arizona special teams.
There are defensive struggles, and then there is Arizona's upset win in Seattle.
San Diego puts up its best defensive performance of the season, showing that you can limit the Broncos' offense by limiting yards after the catch. Of course, it helps when Wes Welker isn't on the field.