After hearing Julius Peppers praised over and over as the best free agent available, the best defensive lineman in the league, a "beast of an athlete," etc., I decided to compare his output with that of Kyle Vanden Bosch. I used the seasons 2005 through '09. Vanden Bosch was pretty much lost in the shuffle in the early part of his career with Arizona, and then injuries would have put him out of the league for good except that Jeff Fisher and the Titans signed him for the '05 season and his career immediately took off.
For the five seasons from 2005 through 2009, Vanden Bosch, 31 years old, had 268 tackles and 38.5 assists. He missed a significant chunk of '08 due to injury.
In the same time frame, Peppers, 30 years old, had 238 tackles and 51 sacks.
Who's the better player? I'd say it's pretty much of a toss-up with an edge to Vanden Bosch because he plays hard every down while Peppers is part of the extremely large contingent of black defensive linemen who have a motivation problem despite the big bucks they're paid.
Peppers was signed by the Bears for 6 years and $79.8 million, with $40 million guaranteed. Vanden Bosch signed for 4 years and $26 million, I don't know how much is guaranteed but he does get $10 million of that in 2010. Overall I'd say the Lions got the better deal.