This game is getting kinda bad, unless you're spending a large amount of time to grind gold or spending serious money to buy it, it is getting rather impractical to do much over rank 20. Managed to get one good deck but quest don't support it, have fun losing all your ranking as you try to finish it...
Are you playing the same game I am playing? Trump just started a brand new account at the beginning of this month and is playing it in ranked. Yes, he got a little lucky on his first couple packs he unlocked (getting a cabal shadow priest and a few support priest cards). He also got decent card selection choices in most of his arena runs (using the gold he unlocked via quests), which has allowed him to open up more packs.
He has opened around 45 packs since the beginning of this month and is at around rank 8 using essentially free and common cards with just 9 rare and 2 epic.
As for losing your ranking trying to finish a quest that you don't have a good deck for... Why the hell are you playing it ranked?!?!! Play your crappy decks outside of ranked play to finish your quests, or mulligan you quest to try and get a different one that you have a better deck to do. Never play use a crappy deck in ranked play and you won't be losing your rank trying to finish a quest.
I just started playing a few arena games again. My first two I had real crap choices (for either cards or character). For instance I had a choice of Shaman, Warlock, or Warrior in one run, so went with Shaman, only to get the crappiest of crappy cards (I mean really bad choices, just 3 cards that were all useless on their own or useless in my deck that I had going being way to high a mana curve, like for instance a choice between two 9 costs cards and a 4 cost Jeeves). Needless to say that deck one a total of 1 match.
My second run I manage to get a Mage (awesome!), and then proceeded to not get a SINGLE SPELL. I am not joking here. I did not have a choice of a single spell out of all the cards it gave me. And not only that, the cards were not even decent cards (not a single card that would let me draw more cards, not a single card that enrages). What is bad is that I selected 3 early spell damage cards assuming I would have to get a couple good damage spells (these were not useless minions, but there were better choices if I had known I would have even been given the choice of a single spell). That deck didn't win a single game.
On my third run, I finally got both a good character and good choices for cards (in fact very good). It was a Paladin and I essentially had a murlok rider deck (with a mukla's champion to boot). That deck steamrolled.