Mishy#1973
Got in a couple of days ago. Thus I only have a mage and priest deck. Kept playing mage from the tutorial into constructed arena and didn't have much trouble until I got to plat, then got destroyed by a priest deck. Immediately hit the play again button and met the same guy... who repeated the destruction. I stopped, re-evaluated, then shelved the mage, rerolled a priest, recreated the deck that destroyed me, then rode it to master level. However once I reached 1 star master, the tier of opponents completely changed, and I lose as much as I win now.
I don't have the knowledge of enough cards yet to play arena well.