Blizzard's cash cow is starting to produce less milk.
World of Warcraft (Blizzard)
The sharp decline is due to a combination of factors, the most prevalent of which is a drop off of users in the Far East, though Blizzard CEO Mike Morhaime noted the game is still very popular in China.
Also contributing to the drop is the churn that followed the release of Cataclysm, the last expansion pack. Because the game has been out for so long and players have gotten so adept at it, they re-activated their accounts when the expansion was released, devoured it, then once again suspended their accounts.
At the height of its popularity, the game boasted a subscriber base of 12 million players.
Blizzard says it's taking steps to combat the erosion, both by improving content and promotional events it believes will strengthen the player base.
A new expansion pack, Mists of Pandaria, is due out next year. To further incentivize players to come back, the company also announced it would offer free copies of the upcoming Diablo III to those who purchase an annual pass to WoW.
Meanwhile, Blizzard has another persistent world in development (though there's no announced release date for that game), which could help cover any weaknesses WoW shows as the franchise ages.
WoW has been king of the MMO hill for a long time -- and competitors are eager to see it unseated, if only to claim a bigger share of the genre's riches. EA will present the game's biggest challenger to date in December, with the launch of Bioware's Star Wars: The Old Republic, which analysts expect to be a big moneymaker for the company.