GB's plan was to shut down the Cowboy running game and make the Cowboys one-dimensional. It worked. All defensive coordinators want to a) shut the run down and b) force the opponent to pass. The defense can tee off on the QB and the CBs play expecting a pass.
If the Cowboys can run the ball, all sorts of good things will happen. Play action will work, safeties will creep up to the line, etc.
And on the flip side, the Cowboys need to shut down the Vikes running game and make the Vikes one-dimensional.