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The Niners have one of the best groups of front seven defensive personnel in the league. Yet they gave up nearly 22 points a game last year to rank 16th. The greatest breakdown came in the secondary, which gave up 25 TD passes last year compared to 14 in 2009.
Of course, not all things fall on defensive backs. Pass rush has a lot to do with pass coverage. Most quarterbacks don’t throw well when they are on their backs. And when pressured, their accuracy goes down, which results in more incomplete passes and more interceptions. In short, hurrying the opponent’s quarterback tends to make the defense improve in all facets.
In that light, consider the article by Kerry J. Byrne of SI.com, which states that pass rating differential is the most telling stat in determining a team’s success..
The PRD stat refers to a team’s offensive pass rating compared to its defensive efficiency in defending the pass. As examples, Byrne points out that the 2009 New Orleans Saints had an offensive pass rating of 106 and a defensive rating of 68.6. The difference was 37.4, which was the largest among all 32 teams. The Saints won the Super Bowl.
Last year, the Green Bay Packers had a 98.9 offensive rating compared to a 67.2 defensive rating. The gap of 31.7 also ranked first, and the Packers became champs. Last year, the Niners had a minus-10.6 rating, meaning that their defense was worse in pass efficiency than the offense. They finished 6-10.
Of course, the Saints have Drew Brees at quarterback, and the Packers have Aaron Rodgers. But that doesn’t tell the whole story of a team’s difference in rating. As Bryne points out in his story:
“Three teams in the top seven [teams in PRD] belonged to Bill Walsh,” Byrnes writes. “This cluster of San Francisco teams proves that the great genius Walsh…was not that he popularized the West Coast offense. No, the great genius of Walsh was that he popularized the West Coast offense while creating arguably the greatest (and certainly most underappreciated) defensive dynasty in history.
“For 17 straight years, the 49ers never surrendered more than 300 points in a season and they consistently produced very low Defensive Passer Ratings, usually among the very best in the NFL.”
Improving pass defense is a team-wide effort that even carries some responsibility to the offense.