Munoz underwent Tommy John surgery Friday.
Munoz was shut down for workload reasons in mid-September after posting a 3.91 ERA and a 30.9 percent strikeout rate in his 23-inning debut, but the plan to keep him healthy evidently didn't work. A typical recovery timeline would keep him out of action until sometime in the middle of the 2021 season, though he'll still be just 22 years old at that point and will have plenty of time to develop into a shutdown reliever.