Pass rush was good enough for hurries, and even potential sacks, but poor tackling technique allowed quarterbacks to evade sacks and extend plays. There were far too many occasions where the rush got home on time but couldn't finish the job and let the QB slip away. Even occasions where the pass rusher completely whiffed, not even touching the QB when he was within reach. To compound the problem, poor tackling by the secondary allowed for these whiffs to become even worse. What seemed like a sack suddenly becomes a chunk play.
Number 52 was a major violator of the above but certainly wasn't the only one. He got pressure alright. He just couldn't finish the job. He bounced off of a few quarterbacks (and running backs) and made them look like Ben Rothlisberger in the process. The "hurry" stat isn't always the best indicator of a pass rush.
Wagner, Brooks, and Mafe were sure tacklers. Witherspoon could handle everything but large running backs and tight ends. Michael Jackson could handle all sizes. Everyone else had more than their fair share of embarrassing moments. The worst tackling team under the Carroll tenure.