Joe Woods and defensive passer rating

The latest name to surface as a potential candidate for the Eagles' defensive coordinator position is Joe Woods.

According to multiple reports, he interviewed with the Birds this week.

So who is he? Woods has spent the past five seasons as the Vikings' defensive backs coach.

Here are some stats on how Minnesota's pass defense performed from 2006-2010. The numbers indicate league rank in each category:

Are there any conclusions to be drawn here? Not really. In opponents' quarterback rating, the Vikings were very good in 2006 and not so good in 2007, 2009 or 2010.

Not much consistency in terms of touchdowns allowed either. And the Vikings have failed to finish in the top 15 in interceptions in each of the past four seasons.

The Vikings have had a couple of Pro Bowlers in their secondary during Woods' coaching tenure there. Darren Sharper (2007) is one. And the guy who killed the Eagles in Week 16, Antoine Winfield (2008, 2009), is the other.

Obviously there is more to Woods' resume than the numbers listed above. But I stumbled across an article by Kerry J. Byrne of SI.com and Cold Hard Football Facts yesterday that offered a take on pass defense and how it correlates to wins and losses.

Byrne argues that defensive passer rating (or opponents' passer rating, as I named it in the chart above) is a great indicator of overall success.

The Packers (67.2) and Steelers (73.1) finished one and two, respectively, in that category last year. I looked at it a little deeper, and 10 of the top 14 teams in defensive passer rating made the playoffs in 2010. The only two exceptions were the Colts (27th) and the Seahawks (25th). It may come as a surprise to know that the Eagles weren't horrible. They finished 11th (80.8).

Passer rating is an imperfect stat. It doesn't account for game situation or running plays by the quarterback. It's calculated through a formula that requires only five numbers: passes attempted, passes completed, yards gained, touchdowns and interceptions.

But using defensive passer rating certainly makes more sense than overall pass defense, which is still cited way too often and accounts only for total passing yards allowed. The top three teams in the traditional pass defense rankings did not make the playoffs last season: the Chargers, Raiders and Bills.

In case you're wondering how the defensive passer rating numbers compare to Football Outsiders' rankings, they're actually pretty similar. Football Outsiders had the Vikings with the 19th-ranked pass defense in 2010 and the Eagles 11th, compared to 21st and 11th, respectively, in defensive passer rating.

Football Outsiders also had the Packers and Steelers first and second in overall pass defense.

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