nah, something like that happened only in WoD and after that they stopped sharing sub numbers with us
it climbing in TBC, it was stable in Wrath and climbed towards the end, it was steadily going down in cata, but it wasnt a big drop, then it grew a bit in the beginning of MoP and then was going down steadily, then it grew back in WoD and then dropped hard like half a year or a year later and they stopped sharing sub numbers