Around the release of World of Warcraft: Cataclysm, Activision Blizzard repeatedly touted its 12 million subscribers. During yesterday's investor conference call, however, Blizzard president Mike Morhaime revealed that as of the end of March, the subscriber base had fallen from a stratospheric 12 million all the way to a humiliating 11.4 million, a decline of 5%.
Morhaime explained the tiny mass exodus by saying that players were completing the new content in Cataclysm more quickly than previous expansions, and then leaving the game. However, Rift also launched in March, which may have lured away part of those 600,000 ex-WoWers.
Still, if we're talking about part of 5% of your userbase maybe leaving for another game, things are still going well for you.