The Cowboys headed into this season feeling good overall about their offensive line, but problems have cropped up at almost every spot. Injuries have been a factor, and Doug Free has been very uneven in his first season starting at left tackle. But the quick aging of ORG Leonard Davis and ORT Marc Colombo has been a big reason why the team has had virtually no success running the ball this season. Both Marion Barber and Felix Jones have found few holes running behind Davis, who was benched briefly against the Titans, and Colombo, who has struggled with a back injury of late. Both men are 32 years old and have incurred several injuries the past two seasons. They also carry a lot of mass on their considerable frames, and they have tended to wear down more as the seasons have worn on. The Cowboys might be forced to find replacements for both as they keep one eye on next season.