Falter was recalled from Triple-A Lehigh Valley on Wednesday.
Falter had already been named the starting pitcher for Wednesday's game against the Mariners, so his call-up was expected. The southpaw's first four major-league appearances this year came out of the bullpen, but he made two starts in Lehigh Valley and is expected to be stretched out to around 60-to-65 pitches. If Zack Wheeler (undisclosed) and Zach Eflin (illness) are cleared to return from the COVID-19 injured list soon, Falter will likely return to the minors or the major-league bullpen following Wednesday's start.