They added a system which limits the top league based on "points" in your card collection. So as I was able to easily reach diamond leagues (occasionally champion III) with my current deck, I was left to gold III with my deck. It felt humiliating as I felt I was good at the game and was able to make great decks for the games, but now I should start buying more decks & cards to get in higher ranks.

I'd rather sell my cards and do something useful with the Hive hanging around on the account :)