Martinez is sidelined at Single-A Delmarva due to a hamstring injury, Jonathan Mayo of MLB Pipeline reports.
Martinez has not been placed on the injured list, but he has not played in a game yet this season for the Shorebirds. The 18-year-old outfielder hit .125 with a 48.4 percent strikeout rate in 25 games at Single-A last year, but he has always logged high walk rates while being young for his levels, and there is plus raw power potential as he fills out his 6-foot-4 frame.