Falter was optioned to Triple-A Lehigh Valley on Sunday.
Falter was called up to make his third major-league start Friday against the Mets, but he was charged with the loss when he gave up five runs (two earned) in three innings. The southpaw has a 5.18 ERA and 1.27 WHIP in 48.2 innings over 28 appearances (three starts) in the big leagues over the last two years, but he's struck out 17 in 10.1 scoreless innings over three starts with Lehigh Valley this season.