The running game rearely beats you in the NFL today. The passing game is much more dangerous which is why you need to optimize your DL to attack the passer not stop runners.
And yet both of the teams in the SB have strong running games. The death of the running game has been greatly exaggerated. With the exception of the Packers and Colts, every team in the playoffs this year had a strong running game.
If you cannot stop the run and have to bring extra guys into the box, you can get torched with the pass.