But it's not getting back to the same status quo.
Take the time between 2.5 and 3.0 and the time between 3.0 and 3.1. The game is more dead now then it was before the expansion pack at it's lowest moment.
It's natural for MMO attrition to happen, especially when an expansion pack doesn't revitalize the game. We're seeing it in action.
I'm talking about expac status quo. Not patch to patch. When 4.0 comes out, game will shoot back up to same numbers as 3.0. I'd also argue that the game had much lower log in numbers during the 2.55-3.0 time frame than it did during the 3.05-3.1 time frame but there is 0 way to prove that one way or the other.