Moreover, and this should ring a bell to all , at this point, a complete leak and fake of Warlords of Draenor should have been unleashed on the internet... but for now, we just have a title and wild speculations...
As for the Dark Below... Madness unleashed and lots of " leak ".
Remember, for Cataclysm, even Boubouille went as far as to list what would be in the expansion before it was revealed. For Warlords of Draenor, we got nothing, nada, void. We barely know what it is about. For Pandaria, we gots a lots of fake but all got on point in common, they agreed that MoP was the name of the next xpack.
Since the revelation of WoD, we got only leak about TdB content. Which is... weird?
I'll throw a random guess. Both The Dark Below and Warlords of Draenor are WoW related. The first one is the next xpansion pack. The second one is a campaign / addon using wow ressources and player's character that can be played on mobile devices.