The team announced Thursday morning it had recalled Diekman from Triple-A Lehigh Valley. To make room for him on the 25-man roster, the Phillies designated right-hander Dustin McGowan for assignment.
The Phillies optioned Diekman on June 4 because he had struggled in 25 appearances, posting a 6.75 ERA, which remains the third-highest ERA among 142 qualified relief pitchers in baseball. However, Diekman threw seven scoreless innings in six appearances in Lehigh Valley. He allowed five hits, one walk and struck out seven. He also picked up three saves.
McGowan became the first Phillies relief pitcher in baseball history to allow five home runs in an appearance, which happened Tuesday in a 19-3 loss in Baltimore.