So Funcom should be commended for apparently drawing some of those WoW players away to play Age of Conan: Hyborian Adventures, which launched in late May. Blizzard president Mike Morhaime said during an Activision Blizzard earnings call on Thursday, "Age of Conan released with some initial success a couple of months ago, and we did see some of our players leave to try the game. However, we've seen about 40 percent of those players return to World of Warcraft."

In about a month's worth of time, Funcom's Age of Conan garnered 700,000 subscribers, according to the developer. Morhaime said that players that leave WoW are often drawn back because of the content and service that Blizzard provides. "Any massively multiplayer online game that launches today isn't just competing with the amount and breadth of content that we launched with back in 2004," Morhaime stated.

He said that other MMO companies entering the market are also competing with the service and content that Blizzard has been honing within World of Warcraft for nearly four years. Morhaime expects that when the next WoW expansion Wrath of the Lich King launches later this year, more players will be compelled to return to WoW, which currently boasts 10.9 million subscribers.

Morhaime added, "Another competitive advantage is our ability to amortize our development costs across more than 10 million subscribers spread out over three continents."He also described the userbase as a "sales force" of satisfied customers who spread the WoW gospel.