The Pittsburgh Steelers may have lost right guard David DeCastro, who reportedly has at least a torn medial collateral ligament in his right knee. If DeCastro, who was the Steelers' first-round pick in April, also has an anterior cruciate ligament, then he will be out for the season, ESPN reported Sunday citing a team source. DeCastro will undergo a MRI exam Sunday to determine the severity of the injury. If it is a MCL injury, he would miss about eight games. The Stanford product hurt his knee while blocking during Saturday's exhibition game against the Buffalo Bills.