Don't use Hearthranger for draft, use Heartharena. You'll get better decks, because it checks synergies too, not just card value. Before the update I played some arenas with silverfish and decks drafted with Heartharena, and the lowest I got was 2 wins, and the highest was 7.
But with the new meta out, and vision A.I.'s curent overall performance, I really don't recommend experimenting with arena.