I dunno, it sure does seem like quite a bit of traffic from outside the country was focused directly at the Los Angeles area last night:
Attachment 1363
If the problem was that only Draenor was overloaded then only Draenor's world server would have been crashing (and it probably was on numerous servers), but playing last night in low level instances -- separate from any of the world servers -- I was feeling a tremendous amount of server lag even after the maximum capacities had been lowered, and I was playing on a realm in the Chicago datacenter. However, this morning at 4:30AM there was still an 1100 person queue to get into Sargeras, but once I was inside the realm there was zero lag at all because the DDoS had already ended (IPViking showed no abnormal activity).