ESPN Power Rankings

To say that "the defense is playing the way everyone thought it would", and basing it on the past 4 games, is nothing more than lazy journalism and doesn't begin to tell the entire story.

vs Baltimore: the Ravens forced 5 turnovers, taking 2 back for TDs. Defense's fault? Hardly.
at Tampa: 14 pts allowed, and played very well (second quarter hiccup notwithstanding)
at Pitt: ok, hard to say much good about that defensive effort
vs Cinc: played pretty darn well to hold the Bengals to 10 points through 3+ quarters, especially considering the pressure put on them by our offense's failure to score points

The Saints defense has been mediocre all season long. People just overlooked it because the offense is so good and generally plays error-free football. The biggest turnover culprit in the Ravens and Bengals game was Drew Brees. He had two bad games. The first is somewhat understandable because Ravens defensive coordinator Rex Ryan is as good as his father and they continue to have one of the best units in the league. The Bengals is less understandable but even great quarterbacks have poor games once or twice in a season.

The analysts know Drew Brees is not the problem for this football team. They know, given his track record, he will bounce back. The defense will not as they have been consistently poor. So when you go to project the Saints' chances down the stretch run, are you going to weigh Drew Brees' two bad games as a greater factor than a defense that has struggled with all but the most timid of opposition? Of course not.