Just because I've been pimpin' him in another thread, I think Adam Oates gets pretty underrated. I think the fact that he moved around so often had something to do with it (Mark Recchi suffers from this as well IMO). It's hard to think of a guy as a "franchise player" when they play for so many teams.
I think the other problem is that people see the great goal scorers Oates played with (Hull, Neely, Bondra) and assume that they helped him rack up the assists.
I think it was the other way around though - most of those guys had career years when given the opportunity to play with Oates.