All I can go by is what the calendar shows to ME and also what Kalviery said (quoted & linked below) in regards to event times.
I can understand the need for the calendar to reflect what dates or times it is using to mark an event – in this case, saying that the times are Pacific.
I also think that looking at the calendar as strictly being for the game itself, rather than for me personally, helps me keep track of event times.
Since the old Forums were shut down, I cannot link to the post directly, but here is the Wayback Machine capture of it.
Reply from a player:
double check your time, is it set to server or local?
Kalviery’s response:
This won’t really matter, my realm is 11:28 AM Local and 12:28 Realm. However, events start globally at the same time now and that is Pacific Time.This is done because of the cross-realm capabilities. If you go from a realm where the event is started to a realm where the event has not started then you could lose event related items. So they all start at the same time to avoid that problem
Link: https://web.archive.org/web/20190707083938/https://us.battle.net/forums/en/wow/topic/20769667734