If the offense is healthy and running like it should, that will immensely help the defense.
Teams won't be content to run the ball and play safe like last year. The Cowboys were an easy 24-13 victory for other teams because they know the Cowboys weren't a threat to score. Punts were no big deal for oppoents. Turnovers dried up for Dallas' defense, and they wilted under the number of snaps.
Now, the Cowboys are going to average 30 a game, so teams have to cut loose. A punt might be close to a turnover against Dallas.
And the run game will grind the clock to nothing, just like in 2014.
I think this team is better than 2014, in fact. Better offensive line, better backs, better home run potential, better secondary, better QB group. If Marinelli can get the front 7 to play average, it's a more complete team.