Garrett was placed on the 7-day injured list with Triple-A Jacksonville due to an impingement in his left shoulder, Barry Jackson of The Miami Herald reports.
The southpaw last pitched for Jacksonville on April 26 and struck out seven batters over five strong innings, but the issue apparently cropped up after the start. The 24-year-old's injury could cost him another chance at proving himself in the Miami rotation, as top prospect Max Meyer is now in line to get the next opportunity if it arises while Garrett is sidelined.