Nationals activate DeRosa, recall Lannan from AAA
Lannan, Washington's opening day starter in 2009-10, is 2-0 with a 3.46 ERA in two starts this season with the Nationals. The 27-year-old left-hander is expected to join the rotation when Stephen Strasburg is shut down for the season.
DeRosa, who missed the last 25 games with an abdominal injury, is batting .152 with six RBI in 34 games this season.
In 10 games with Washington, Leon is batting .250 with two RBI.
The Nationals also reinstated catcher Jhonatan Solano from the DL and optioned him to Double-A to Harrisburg.