Tedy Bruschi's defensive index is back

When judging total defense in the NFL, many often point to yards allowed as the primary measure for a unit's effectiveness. ESPN analyst Tedy Bruschi sees that as a flawed analysis.

Bruschi has put together his own formula on how best to measure defense, and it goes back to five core principles he was taught as a player:

  1. Don't let them score (points per game; only on offensive plays from scrimmage)

  2. Take the ball away (the importance of turnovers)

  3. Get off the field (third-down conversion rate)

  4. Situational defense (red-area efficiency)

  5. Disrupting the franchise QB (sacks)

By rating each NFL team in these categories, it produces a league-wide defensive index that purposely overlooks yards allowed as a measure to gauge the effectiveness of a defense. Why no yards? With more spread offenses and prolific passing attacks in today's NFL, Bruschi views yardage rankings as overrated because many teams have the ability to go from 20-yard line to 20-yard line on a regular basis.

Thus, Bruschi's "defensive index" places a heavier emphasis on the growing importance of "situational" football.

Through seven weeks it's notable to see the Detroit Lions at No. 1 and the defending Super Bowl champion Seattle Seahawks at No. 32.