Nationals reliever Craig Stammen will undergo surgery, likely out for season

Nationals' reliever Craig Stammen will require surgery on a torn flexor in his right elbow, according to an announcement from the team. Although the exact timetable for his return is not yet known, he is expected to miss the remainder of the season due to the severity of the injury.

Stammen, 31, made five appearances to begin the season, pitching four scoreless innings in his seventh season with Washington. The right-hander was slated to be a late-inning option in front of Drew Storen, though his absence will cause the Nats to call upon arms like Blake Treinen, Tanner Roark, Felipe Rivero and rookie Rafael Martin as options in their bullpen with Casey Janssen on the disabled list.

Rafael Soriano, who logged innings in the back end of the Nationals' bullpen last season, is still available on the free-agent market, though it remains to be seen whether or not the team will pursue a reunion with Soriano in Stammen's absence.

Washington's bullpen underwent a significant overhaul this winter, with Soriano, Tyler Clippard and Jerry Blevins departing and Janssen signing with the club. Other veterans on the free agent market include Jose Veras, Brian Wilson and Jose Valverde, so one of those pitchers could be signed to provide depth for the Nats at Triple-A.

After starting his career with the Nationals as a starter and struggling mightily, Stammen joined the team's bullpen in 2011 and has been one of its most consistent contributors over the past five seasons. In 191 appearances since 2011, Stammen is the owner of a 3.02 ERA in 280 innings.