Edit: This is NOT to say that Blizzard does not often take advantage of cunning marketing plans. This IS clearly for the purpose of trying to increase revenue and increase interrest within their franchises towards another franchise and property. But this particular marketing strategy have nothing to do with boosting subscription counts for the comming quarter - but it just might in the long run =)
2x Edit: I just sat and read through the company I used to work for and how they handle fiscal quarters and shareholder meetings. Turns out, my former company would already have their numbers for a quarter counted up little over ½ a month before releasing the numbers simply to avoid mistakes and prepeare the representatives to know what questions they will recieve from investors and shareholders in advance.
I can't say for sure weither Activision Blizzard does the same, but color me suprised if it's a guy sitting with a stop watch going "Aaaaaand NOW! Quick, post this number!" by the exact time of release =)