Here's some good stats regarding defensive lines:
FOOTBALL OUTSIDERS: Football analysis and NFL stats for the Moneyball era - Authors of Pro Football Prospectus 2008
GTripp will be able to explain these stats better than me ... I know he frequents this site.
Anyways, the data shows our defensive line was ranked 17th last year overall. That puts us above NE, SD, GB, JAX, and DEN, as well as others.
Interestingly enough, those stats rank us #1 last year in the 10+ category -- a measure of LB performance.