The Phillies designated Keller for assignment Wednesday, Robert Murray of FanSided.com reports.
Keller gave up one run in three innings during his MLB debut July 25 but has coughed up 12 runs in just 9.2 frames since returning to Triple-A Lehigh Valley. The 32-year-old righty will now lose his place on the 40-man roster to make room for Nestor Cortes, who signed a major-league deal with the Phillies on Wednesday.