These accounts seem to get hacked all the time.. How does this happen? Super easy password, keylogger, details sold by employee or social engineering.. I don't believe it could be brute forced..
Same with BT, TalkTalk and AOL email accounts loads of people have them "hacked"
All the main gaming sites like Blizzard, Valve, Microsoft, Ubisoft, EA have app authenticators. Please make sure you use them everyone!
Didn't realise Blizzard had one as well, thanks - just installed it.