Philadelphia optioned Joe Savery to make room on the roster, and it also placed outfielder Laynce Nix on the 15-day disabled list and transferred Justin De Fratus to the 60-day DL. Reliever Brian Sanches was optioned to Lehigh Valley.
Diekman, a 30th-round selection in the 2007 First-Year Player Draft, has posted a 0.59 ERA in 13 relief appearances for Lehigh Valley this season. The 25-year-old southpaw hasn't started a game since 2009, and he's notched a 12-16 record with a 3.78 ERA for his six-year Minor League career.
Valdes, who has pitched sparingly in the big leagues in each of the past two seasons, notched a 1-2 record and a 3.86 ERA in his first 11 appearances for Lehigh Valley. The 34-year-old worked in 13 big league games last season for the Cardinals and Yankees and posted a 3.00 ERA.
Luna, meanwhile, hasn't played in the Major Leagues since 2010. The utilty man is batting .274 with one home run for Lehigh Valley, and he's a .279 hitter for his Minor League career. Luna, 30, has batted .265 in 311 big league games played with St. Louis, Cleveland, Toronto and Florida.
Spencer Fordin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.