DeCastro would have likely started all year, but for a preseason knee injury. In past years, an injury such as the one DeCastro sustained Aug. Steelers general manager Kevin Colbert and coach Mike Tomlin could barely contain themselves on draft day when David DeCastro fell to Pittsburgh at No. 24. But with modified injured reserve rules implemented this season, DeCastro was placed on an IR list that allowed him to come back after eight weeks. The Steelers instead chose to ease him into NFL life. The Steelers have been shuffling the line all season, and the aggravation of Willie Colon’s knee injury caused the latest round. Tomlin said cornerback Cortez Allen has a hip flexor injury that Tomlin which could keep him out of the Cowboys game.