Unless it's gotten better, it's super easy for China.. My traffic to EU World of Warcraft servers got hijacked all the time. I don't know if it was malicious or just incompetent Chinese ISPs, but you feel that extra latency when it goes through China.
But this wasn't a bgp redirect, this was blizzard doing something... if chinese telcos acted as if they were blizzard telcos, there would be bgp filters and a lot of outrage in a matter of minutes. This is not a small deal.
