Felix Jones' hamstring tweak this week comes at a bad time. Already without DeMarco Murray for the season, it leaves Jones and Sammy Morris as the only backs currently on the roster. A week ago was Morris' first game this season with any NFL team. (At presstime, reports surfaced that the team was ready to promote Chauncey Washington from the practice squad, but he has a total of four regular-season carries in his NFL career — all of which game in 2008 with the Jaguars.) Jones was just starting to break out, logging his second straight 100-yard rushing game (he had only two such games in his career prior), before getting hurt. But as Cowboys fans know, this is an annual ritual. Jones has been subject to sprinter-type injuries such as groins and hamstrings throughout his career and it has taken him out of games and affected his stamina when he does play. He has had 25 offensive touches in a game only twice in his four NFL seasons. That lack of stability — and Murray's penchant for getting hurt in college — likely means running back will remain a need in the offseason.