Watching the Green Bay Packers pass defense get picked apart by the Chargers last Sunday reminded me of the 2009 season. Not the 2009 playoff loss to the Cardinals, but the regular season loss to the Steelers in Pittsburgh. That season presented one mystery to me: how could a pass defense ranked No. 4 overall that season get shredded in their playoff loss? I never came across a satisfactory answer, except that it showed how great Kurt Warner can be. But that isn't an explanation that can be used to explain every poor defensive performance in 2011.
Based on the team ratings at Football Outsiders, I chose their games against the top 2 and bottom 2 pass offenses that they faced (have so far faced) in those seasons. In 2009, two of those games happened to be against the Vikings and Lions, so I chose the worst QB rating allowed from those two games. Then I compiled a table of key stats from those games.
In 2011:
| Team | FO Rank | Yards | QB Rating | TD | INT | Sacks | QB Hits |
|---|---|---|---|---|---|---|---|
| New Orleans | 6 | 419 | 112.5 | 3 | 0 | 3 | 6 |
| Carolina | 9 | 432 | 72.0 | 1 | 3 | 4 | 7 |
| St. Louis | 29 | 328 | 76.9 | 0 | 1 | 3 | 5 |
| Denver | 31 | 273 | 87.1 | 3 | 3 | 1 | 3 |
In 2009:
| Team | FO Rank | Yards | QB Rating | TD | INT | Sacks | QB Hits |
|---|---|---|---|---|---|---|---|
| Dallas | 3 | 251 | 78.0 | 1 | 1 | 5 | 5 |
| Minnesota | 4 | 271 | 135.3 | 3 | 0 | 0 | 1 |
| Detroit | 31 | 213 | 30.5 | 1 | 4 | 2 | 3 |
| St. Louis | 32 | 164 | 75.2 | 2 | 1 | 1 | 7 |
One side note is that the defense received a good opponent adjustment in 2009 because they happened to face a lot of very good pass offenses that season. But in 2011, they haven't faced as many of them.
Overall I see a lot of similarity in these games. The sacks and quarterback hits are about the same, and so are the touchdowns allowed and interceptions made. The only quarterback rating that really stands out is the pasting they put on Matthew Stafford back in his rookie year.
The one stat that really looks different is yards allowed. I took some stats from the 2011 season, projected them out to a full 16 games, and compared them to the 2009 season.
| Season | Pass Attempts | Comp. % | Yards | TD | INT |
|---|---|---|---|---|---|
| 2011 | 638 | 59.2 | 4794 | 32 | 32 |
| 2009 | 540 | 54.4 | 3218 | 29 | 30 |
There's no simple explanation for why the completion percentage against the defense is so much higher, but a lot of the yards also come from a lot more pass attempts against them so far this season. I do think it's very important to note that the Packers are allowing almost the same number of touchdown passes as they've done in previous seasons, and they are still intercepting a lot of passes.
There's obviously room for improvement, but I was very surprised how similar these stats were compared to similar games from prior (and seemingly better) seasons. Maybe this is a pass defense that can become a lot better very soon if they can improve their communication issues.