That's not totally fair. He's not Warren Sapp or John Randle, no, but he's one of the best three-technique defensive tackles in the NFL right now.
He has an impact even when he's not collecting sacks because I've witnessed him get triple teamed on some passing downs. That means that you have three OL blocking one-on-one on the other pass rushers, plus a man out of coverage, whether it's a TE or a back.
At that point, it's on someone else (Calais Campbell, anyone? Joey Porter?) to defeat one man and get to the QB.
I was at my in-laws' for today's game, so I can't say whether or not this happened today. But Dockett has an impact even in games where he doesn't show up on the stat sheet because of the attention he demands.
If you're putting him in the same breath as Julius Peppers and Mario Williams as a pass rusher, yeah, he's overrated. But I'd put him up with any other three-technique tackle in the NFL.