As much as they are still a big part of this team, I agree they have fallen off and that they are not the force they were a couple years ago. Hank has weathered better than Dan, who is certainly not worth his cap hit this year or last.
When you see opposing coaches recognize that the Sedins are less a danger than a line with a $600K/yr Santorelli on it, you know the twins have dropped off. Also Santo at +14 to Hanks +5 is a telling stat.
What I observe are two slow skating very talented players who's style has been scouted at length and every team now knows how to defend against. Their lack of speed and ability to beat players one-on-one makes them predictable. They are still effective on the PP because of the extra room to maneuver but 5 on 5, they are not nearly as effective. If they can only be effective with one or two players after all the combinations tried, who is the real performer...Burrows or the twins?