Milner was optioned to Triple-A Lehigh Valley following the conclusion of Monday's doubleheader against the Mets, Scott Lauber of The Philadelphia Inquirer reports.
Milner will head back to the minors after failing to make an appearance during his short stint with the big club. Through 25 games at Triple-A, Milner has posted a 2.39 ERA and 1.34 WHIP with 28 strikeouts over 26.1 innings.