Alcantara was called up as part of a batch of September callups Saturday.
Alcantara made a single start for the Marlins earlier in the season, giving up a run on three hits and five walks in five innings against the Mets in late June. It's unclear whether he'll join the rotation or work out of the bullpen, though he's only been a starter for Triple-A New Orleans this season, posting a 3.89 ERA in 19 starts.