I wanted to give the folks who throw these terms around a better way to think about how the whole Draenor thing works.
We aren't traveling to the past, or an alternate branch of the past that Garrosh created once he and his cohorts stepped through (lel many-worlds quantum physics interpretation). There is no alternate Azeroth to speak of, relative to this Draenor. Draenor was brought to us. The little area of spacetime that consists of Draenor 30 years ago was merged with our current overall spacetime. Think of it as old Draenor being copypasta'd into the place where Draenor used to be in our current timeline, before it was blasted into the Nether (this isn't factual, but I like to think that's where Draenor ended up). This is what Kairoz did, or rather, ends up doing.
We aren't time-traveling to Draenor, Draenor is time-traveling to us, and the Iron Horde makes a cross-universe portal to our planet just as the original Horde did. This is why the Legion, and Kil'Jaeden in particular, will end up going apeshit once they find out what happened.
Did I say Draenor enough? Draenor.