Jamal Lewis and Michael Bennett both ran over 100 yards, Deuce had 99. But if you look at their schedule, they played 10 games against teams I would consider to not have an actual full time starting RB (San Fran (2), Arizona (2), Chicago, Pittsburgh, Detroit, Washington, Cleveland, and Minnesota). Michael Bennett was the only guy to go over 100 yards. The other six games (St. Louis (2), Baltimore, Cincy, New Orleans, and Green Bay) there were two 100 yard rushers.
Overall they were 15th against the run. IMO, they were lucky to be that good. It could have been worse if they would have played some better rushing teams (e.g. Denver, San Diego, Jax, Carolina). Here's a nice little tid bit, they played 6 games against THE 4 worst rushing teams in the NFL.