What's the best way to rank defenses?

Is it points allowed? Yards allowed? Turnovers forced? There isn't one right answer, but one of the better methods is to combine a group of statistics and create an index.

ESPN NFL analyst Tedy Bruschi's defensive index does just that, and the Buffalo Bills' defense is treated favorably, ranking second in the NFL behind the Detroit Lions.

Bruschi combines a defense's ranks in turnovers, third-down conversions, red-zone efficiency, points allowed per game and sacks to arrive at his index ranking.

One surprise on the list? The Seattle Seahawks' vaunted defense falling to dead last in the ranking.