Dallas' Frederick won't move from center

The Dallas Cowboys continue to dabble with offensive line combinations. It's latest incarnation has Doug Free at right guard, Jermey Parnell at right tackle and Mackenzy Bernadeau at left guard. The two constants have been Tyron Smith at left tackle and first round pick Travis Frederick at center. Frederick can also play guard, but the Cowboys don't expect to experiment with him the rest of the season.