Sigh.
Okay, let's talk networking. This thing called the Internet -- it's an interconnection of networks. If your traffic passes through a congested network, your traffic will be delayed or dropped. If it doesn't, it will go through fine. You may well have "no Internet trouble" for other locations if the traffic passes in a different direction. Obvious example: The path going to the west coast is going to be different than the path going to the east coast.
And as somebody else pointed out, they didn't necessarily say it was your ISP either. If their upstream providers are getting DDOS'd there's nothing they can do but sit and wait there either.
TL;DR? The fact that you don't detect problems elsewhere means nothing.
Right, it makes much more sense that a problem develops that only manifests itself at off-peak hours after the servers have been live 19 hours without issue because that fits in better with some peoples' desire to have a Blizzard bitch-fest, right?
Honestly, half the people in this thread need to go read up on the Dunning-Kruger effect. You people don't even know enough to know how little you know.