Last year, preseason rankings for NO were the following:
NFL.com: 32
ESPN: 31
Fox Sports: 32
Seven teams finished with a worse record than the Saints, who finished tied with the Chiefs and Bengals. All three of those teams had a worse record than the Dolphins. So I wouldn't put that much stock in those kind of predictions.
That said, my own personal expectations for the season are currently sitting at "Joe Philbin 2.0" so I'm not exactly stoked.
I don't think the Dolphins will come in last; I think it just shows that they are predicted to be in the bottom quarter of all teams (Which I agree with). There could be a miraculous season where last year's rookies play like All-Stars, this year's rookies also play like they are veterans, the coaching is above par, and they get some lucky breaks with turnovers at key times leading to a 13-4 season; but that's not likely.