Not saying that they have, and trying VERY hard to not sound like a homer, but purely for the sake of argument/discussion: What proof do you need?
They have on the last 3. Two in convincing fashion (not to mention one by a dominating defensive win and the other by a dominating offensive win). Every game they have lost has been inredibly close and down the to wire (3pts in each L).
Honestly I'd toss Packers, Giants, and Eagles in the top 3 right now. Atlanta, honestly means nothing to me. I think its smoke and mirrors. Saints SHOULD be way better than their record, but lots of teams can say that. They have the firepower, will and coach to pull out of it though, and I don't doubt that they will.