Pro Football Focus looked at "edge rushers" which includes the outside linebackers of the Green Bay Packers. From PFF:
It’s as simple a formula as ever. You add up all the sacks, hits and hurries a defender gets and divide it by the number of snaps they spent rushing the passer (a stat only found at PFF), multiply it by one hundred and, suddenly, you have a nice, juicy, PRP number to get stuck into.
LB Clay Matthews. He comes in at No. 18. If you think that's really low, don't read too much into it. As far as I can tell, they are counting every pass rushing snap as an opportunity for Matthews to rush the passer. But he doesn't rush the QB on every passing down. Often he drops into coverage, and during the Super Bowl he spent a lot of time spying the quarterback. Just doing what the system required hurt him in this analysis, but obviously it doesn't make him less of a player.
Overall he recorded 74 QB disruptions, which is about 8th overall in total disruptions, and one behind Dwight Freeney (who I don't think does anything except rush the passer). Statistically he's among the best as a pass rusher alone. And that doesn't include how many big turnovers he forces, or all the other things he does for the team.
LB Frank Zombo. On the flip side, came in at the bottom 10 with only 14 pass disruptions in 252 attempts. Same rule applies for him as it did for Matthews, he does more than just rush the quarterback on passing downs, but the stats are also telling the truth. He often is swallowed up by larger offensive lineman, and if he was the full-time starter, I'd only expect him to be good for one big pass rush per game. He's got the skill to become a better pass rusher, but he's going to have to keep improving because he's not a finished product yet.