First off:
Let's lose this 11 million subs, bullshit.
It is, in reality:
4.5 million "Non-Chinese Subscribers" with 6.5 million in China.
THAT is the setup.
With that small "Whoopsie, my bad" of yours cleared up, they've lost almost 1 million customers in the last 6 months (simple math = 900k subs LOST (this take into account new subs & lost subs with a NET LOSS of 900,000 lost subs) was once roughly 5.4 million subscribers) So, let's think about it for a second: You start with roughly (someone correct my numbers where I'm wrong, please), 5.4 million people subscribing every month and you LOSE 900,000 of them, you're down almost 17% in just 6 months. And this is with no true competition, just simple burn out.
Now add in the month before this MMO comes out when all those folks who are (currently) playing WoW with the "Meh, I'm bored as fuck, but this is the only game worth my time. But I hope that Star Wars is good, because I need something new to play...." players and you've got a potential MASSIVE drop in subscribers. Seriously, did you miss the massive ramp up in content production Blizzard has recently pledged for WoW once those 2 quarterly statements showed back-to-back drop of 600k subs & 300k (or was it 400k the 2nd time?) drop and we're still not that close to SW's release? They KNOW what's going to happen: The majority of the fan-base is currently burnt out on WoW, they're looking for the "Next Big Thing" to play & they know that unless Star Wars is s dud, they're going to potentially lose a metric fuckton worth of subs to them.