As you all know, in Rise of Shadows, classes are divided in two sides: Dalaran Defenders and Lesgue of EVIL.
Dalaran Defenders are composed of Mages, Druids, Paladins and Hunters, and present a very classic aesthetic. If we ignore new mechanics and the occasional Dalaran Eye in the artwork, cards like Kirin Tor Tricaster, Keeper Stalladris, Rapid Fire or Duel! have a very plain flavor that wouldn't feel out of place in the Classic set.
Now, EVIL classes are a different story, since each of them callbacks to a specific previous expansion:
Warrior has mechs, wrenches and bombs as a callback to GvG and BDP.
Priest has facelesses, silithids and creatures twisted by the Old Golds to reference WOG.
Rogue has a lot of kobolds, as well as a looter and a pick, as a recall to K&C.
Shaman has a lot of swamp creatures, especially (but not limited to) murlocs, referencing the Witchwood.
However, not a single Warlock card has any thematic relation with League of Explorers. No ancient artifacts, no mysterious curses, no nothing. What's more, there's only one card has something to do with Rafaam at all (besides himself and his scheme): Plot Twist, since Ethereals are good at dimensional traveling.
And... What did Warlock get instead of cool archeology stuff? Demons! And Demons have only been this prevalent in... You guessed! The Classic set!
So, here rests my case. Rafaam is obviously a Dalaran Defender in disguise. We'll see what he's up to.