New Redemption Grab Bag now includes an assortment of 500 cards from five (5) different expansion sets. Available at Cactus website.
Hunters terrify me in Arena probably more than anything in the sense you always have to play around UtH by never over-committing to the board. Playing just one big minion on curve a turn has always worked for me against Hunters.
So with personal Arena experience and after watching a decent amount of streamers, the amount of wins does not have THAT much to do with the amount of rares/epics/legendaries.
Those are the real priorities, so a lack of those will make winning nearly impossible if you try to trade card-for-card.