Appel was placed on the 7-day injured list at Triple-A Lehigh Valley on Wednesday due to an elbow injury, Matt Gelb of The Athletic reports.
Appel has been in the minors for just over a month, but he's now dealing with an elbow issue that will sideline him for at least a week. The severity of his injury isn't yet clear, and whether he's able to return after a minimal IL stint remains to be seen.