Oh, gotcha. That's normal in MMR ranked systems as far as I know (e.g. Overwatch, League of Legends, etc.).
In theory I'm guessing because you're always matched 1v1 with someone of your same MMR in Hearthstone, they don't think you need additional gain/loss balance. If your MMR was off such that you need compensation, you'd just get matched against someone else the system thinks is your equal.
On another note, I hit rank 14 since I figured I might as well play ranked to do a quest. I can confirm that more shamans and a pirate warrior showed up. Only one (dragon?) priest. They kept holding tons of cards, and I assume they planned something evil, but they surrendered before whatever it was happened.