I think the line has played well in the second half of the season so far. I think many people see DD as a problem position because if you cannot rely on your running back to be productive game-in, game-out you will have problems. Just look at the Cowboy offense and how much better their line looks now that Jones is running the ball.
I think this is one of the most important areas to address for the Texans. Dom will make a fine 3rd down back and complimentary back, but if he is your lead back you need some help.
The Texans have multiple problems so I think Dom isn't the only reason we are not a dynamic team yet. We are in year 3 and we need to be patient as we continue to add starters going into year 4. I expect us to compete this year, but there is too much finger pointing to me.