Unlike with Run Defeats, Pass Defeats do seem to correlate pretty well with total pass defense performance. Green Bay, Pittsburgh, and the Giants are the top three teams, and they were also the top three teams in pass defense DVOA (albeit in a slightly different order).
A pass defeat is recorded by the game trackers at Football Outsiders when the defense has a turnover, sack, tackle behind the line on a short pass play, or a tackle/pass defense that prevents a third-down conversion.
In today's pass heavy NFL, stopping the pass is the first priority for a defense. With so many teams forced to pass to keep up with the Packers high powered offense, their opponents are forced to pass right into the strength of the defense. They can't take advantage of the fact that the defense is lousy at stopping the run. And it also highlights an area (the run defense) that they can work to improve on in 2011.
They previously ranked overall defeats by player, and LB Clay Matthews was on the list. Most of the players on it are great, but some of it was a matter of opportunities (i.e. their lousy defense was on the field a lot). Which explains why ex-Packer/current Cardinal LB Paris Lenon is ranked slightly below Matthews.