I would say, there isn't a straight answer like that possible.
DD or the Line, or both. Or is the defense too bad and force them to score every drive? Can the line and Dom get better or harmonise better to get a more constant running attack? It isn't impossible at least.
There isn't a better HB on the roster for now and the OLine needs experience. Both have some more games to develop. Perhaps that opinion is a bit tame, but...