The Saints created turnovers all season, at a rate of more than 2 per game. It has from the beginning been one of GW's primary focuses and every defensive practice starts off with a series of turnover "stations" where the defensive players practice takeaways.
In the playoffs, the Vikings shot themselves in the foot a bit with the number of TOs, but the Saints directly caused at least 3 of them. Creating 3 turnovers in a playoff game is huge. If they can create just 1 or 2 against the Colts, it could easily determine the outcome. Taking the ball away from the other team is about as big a play as you can make.
Amusingly, I just went to NFL.com to look up some stats and replays from the Vikings game, and the headline story is "KINGS OF THE TAKEAWAY."
Quote from the article:
"Sure, some of the balls the Saints' defenders end up with were because of mistakes of other players. But when a team amasses 39 takeaways in the regular season and then adds seven more in two playoff games -- that number could have been closer to 10 had the Saints simply fallen on fumbles by the Vikings in the NFC Championship Game instead of trying to scoop them up -- there's more than mojo working in their favor."