The Nationals optioned Cornelio to Triple-A Rochester following Sunday's 4-2 loss to Atlanta.
Cornelio will return to Triple-A after just over a month-long stay in the big leagues. The right-hander posted a 4.63 ERA and 1.80 WHIP with 16 strikeouts over 11.2 innings in eight appearances in his second stint of the season with the Nationals. His demotion will clear a spot in the bullpen for right-hander Yovanny Cruz, who was one of four players the Nationals acquired from the Yankees on Sunday in exchange for first baseman Luis Garcia.