It is very tricky question. It can be the fault on both sides. As you, I also noticed that the players are leaving the World of Warcraft. There has been small number of patches and upgrades, and it is Blizzard’s fault. They should be better informed about the player’s wishes. They must be active and release more upgrades for the game, or they will loose many more players. Therefore, I think that the fault is completely on Blizzard’s side.