Muller was hit in the right (non-pitching) hand by a comebacker last week and is not listed on Triple-A Gwinnett's list of planned starters for the next five days, David O'Brien of The Athletic reports.
The team is trying to get a splint made that will allow him to pitch, and he has not been placed on the injured list. It's unclear when he will be able to return, but Muller had been excellent lately at Triple-A. Over his last eight starts, the big lefty had a 2.25 ERA, 0.88 WHIP and 61:9 K:BB in 52 innings.