Combo priest got to be the strongest deck in the game atm, so idk what you talking about. Multiple top 5 legends with it already. One of the best winrates according to HSReplay and you need to consider that the deck is very skill intensive, so that automatically lowers the winrate of the deck by people who are bad at playing it.
I don't even know why is it called combo priest in the first place. Combos usually kills you the turn they are performed. And I don't see really anything special with that, I faced two at rank 5 (first and only priests met) and they both conceded due the impossibility of gaining the board back. Happy it's a thing then, easy wins.
IDK about easy wins, i guess it depends on your opponent. This is on rank 1/legend. Deck is definitely a thing.