It's a little of both, honestly. And no, I don't think most characters could have held onto sales like Dick did during the Ric saga.
It's been a while since I looked at the sales charts, so maybe I'm remembering wrong. But if memory serves, the title was only selling in the 30-35K range anyway when Ric first began, and didn't see that big a drop for the first....year?...or so.
I don't remember the specifics of the sales chart, but I *do* remember being annoyed that Ric was selling as well as it did, and having discussions here with folks about how we could support Nightwing without buying the title.