Having three talented running backs has helped the Cowboys through injuries. It also has created competition, not friction, with Marion Barber, Felix Jones and Tashard Choice. Dallas ranks fourth in rushing among NFL teams, averaging 153.3 yards per game. ``They've all shared time,'' running backs coach Skip Peete said.``If everybody gets an opportunity to play, you better shine when you're in there.'' Barber has 344 yards and three TDs on 72 carries; Jones has rus...