Danault is pretty good, he's a shutdown guy matched with two wings who are good fore-checkers and have talents of their own. That allows him to hang back lean defensive yet jump up it they win the puck.
I think as a center on that type of line he works very well. I don't think expecting him to be more than that is going to meet those expectations.
Much like Goodrow, Coleman, etc, the overall team allows certain players to excel. Not sure I see the fit on the Rangers for Danault as a 2nd line center, yet that is where his cap hit will be. Similarly for the other names often thrown out there.
To put it another way, Rooney, Blackwell on Tampa or some other playoff team are seen in a better light, and quite honestly those two fit on the Rangers at a super low cap hit and they still get overly criticized, even when they are already signed for next year. They are not going to solve the Rangers issues yet they are also not the problem, which is what these other guys if imported will be grouped with as well, just at a much higher cap hit