I strongly disagree with that statement. Marcus Stroud and John Henderson are much more dominating. Kevin Williams is on par with both these guys, but Pat Williams is aging and can't really keep up. In reality, Pat Williams in his prime wasn't as good as Stroud and Henderson are now.
Well, Williams and Williams are very good. The group in Oakland does a good job, as well. I'm also partial to the Steelers' Dline. However, Stroud and Henderson are both monsters and all-pro worthy every year. It is very hard to argue with their overall quality.