After watching the Denver Broncos' defense get slaughtered by the New England Patriots and Tom Brady on Saturday night, it's hard to believe any team has much of a chance of slowing them down. The Baltimore Ravens finished the regular season as the best pass defense in Football Outsiders' defensive DVOA ratings, so one would believe that they have a better chance than any other team. However, the Ravens also finished 28th on defense in our variance stat, which measures how consistently good the defense was. What that means is that while the Ravens have played some phenomenal defensive games (for instance, destroying Mark Sanchez and the Jets in a memorable Sunday night matchup), they've also played some very average games.
More importantly, the Ravens played a team with a top-10 DVOA passing offense only four times this season: San Diego, Houston and Pittsburgh twice. None of those teams were in the top five, and the Ravens' defense averaged just an 8.0 percent DVOA against them, a decline in effectiveness of about 25 percent.