Last season. Rush led a more capable Cowboys team and didn't leave the defense to play by itself.
Yes, they had better stats, but Rush nearly always moved the offense, giving them time to rest.
Rush didn't need to put up 30 points because he made the Cowboys a complete team and the defense could focus on stopping the opposing team without having to play the entire game.
Some of the fans think 30 points on offense is great, but if the opponent scores 31 because the Cowboys offense can't keep the opponents offense off the field, it's not that good.