On the Saints defense, I think they can, but they have to get Gore going early to open up the play action and take pressure off of Alex. You know NO will be bringing heat on #11 so they have to put in a lot of check down/screens and quick 3-step drops for Alex. Still take shots deep, but for the most part, just 5-yard them to death and keep Brees off the field.
Also, I know this is an offensive thread, but defensively, I would have Aldon Smith in on every down for pressuring Brees.... It's night and day the difference between Brees when he's getting consistent pressure and when he has all day, and the Niners have the personnel to bring the heat on the mighty Drew Brees.
Cool 49ers playoff insight here: The Bay Area Sports Journal