Stephen Strasburg throws, status remains unclear for next start

ST. LOUIS - Stephen Strasburg threw, albeit casually, for the first time since leaving Sunday's game with upper back tightness.

"He played catch," manager Matt Williams said. "We'll see how he comes out of that. He didn't feel anything abnormal today, and so we'll do a little more of that tomorrow and look to get him to a bullpen (session)."

Tanner Roark made his second minor league start last night since the Nats optioned him on Aug. 25. However, the right-hander's outing at Double-A Harrisburg was shortened to only 34 pitches over two innings.

"Depending on how Stras comes through, we wanted to limit Tanner so he would be ready to make that start if need be," Williams explained. "So we abbreviated his start yesterday to give him three day's rest to be in line for Friday if need be."

Williams indicated that they could possibly skip Strasburg's turn and then slot him back in the rotation when his back discomfort fully clears up.

Williams disclosed that right-hander Aaron Barrett's ailing right elbow requires surgery. The second-year reliever spent nearly a month on the 15-day disabled list from June 12 to July 10 with a right bicep strain. He returned to the Nationals for a few weeks before ending up back on the DL in early August with a sprained right elbow.

Famed orthopedic surgeon Dr. James Andrews is treating Barrett.

"Right now, they're looking at Tommy John (surgery)," Williams said. "We'll have a better indication on that later this week."

Right-hander David Carpenter was transferred to the 60-day DL so the Nationals could call up catcher Pedro Severino from Harrisburg. The 30-year-old Carpenter was acquired June 11, pitching to a 1.50 ERA over eight appearances out of the bullpen before landing on the DL with right shoulder inflammation on July 12.

Finally, Denard Span underwent successful surgery in New York today to repair the torn labrum in his left hip.

"They did a little shaving of the bone to clear some space for him," Williams said. "He'll recover for a few days and then get to the therapy part of it, which starts almost immediately."

Span's recovery process is expected to last four to six months.