As a Saints fan, I'd give us a chance, but not a good one. Mainly because SP isn't going to outcoach Belichick.
Now, I wouldn't use that week 2 game as any kind of reference point...the defense was a trainwreck then. It was after that game they turned it around....they gave up I believe 1100 yards the first two games of the season, then went on a dominant run where they were the #1 defense in the league for a long stretch before levelling off a bit around week 12 or so, in large part because of injuries.
Which brings me to the big problem. We have I believe 17 guys on IR, and a lot of those guys are starters, or at least guys who would play a lot of snaps: Fairley, Breaux, Klein, Anzalone, Vaccaro, Fleener, Okafor, Strief, Stupar, Hughes, Kuhn. Then we have Hendrickson and Hoomanawanui that missed the last game, and Armstead, Kelemete and Kikaha who got hurt last game.
So that's a starter at corner, the #1, 2 and 3 guys at LDE, a starting DT, a starting left tackle, two starting LB's, a starter at safety, a starter at TE, the would-be 6th man at OL, the replacement 6th man at OL, starting FB, a solid depth DT, the special teams captain and 4th LB. The injuries have been insane and I'm not sure there's going to be enough manpower left to get win more than one playoff game.
We are also relatively thin at WR and as somebody mentioned, if you take Kamara out of the game the offense loses a lot of its juice since he is not only a starting caliber RB but the closest thing we have to a zone beating slot WR. As good as the defense has been this year the offense has been a bit of a letdown at times compared to what we've been used to seeing over the last 10 years.
I think we could beat any of the NFC teams at home. We could probably beat Philly on the road since they're stuck with Foles now. I don't see us being able to win at Minnesota or the Rams. I think we could beat any AFC team, except the Patriots.