Yeah, the DEC at the novice or Bronze 3 level can be less than 1 DEC per win. Higher up in Bronze you can start getting 5 DEC per win and even up to about 12. At least, that was my experience. And it's fairly cheap to rent the necessary cards to get to that level. There's useful commons that will get you there. Then, just start investing in higher power cards. It's a slow grind at first, but then it "clicks".