Yankees manager Aaron Boone said Tuesday that Grisham has been diagnosed with a "moderate" right hamstring strain, Brendan Kuty of The Athletic reports.
Grisham landed on the 10-day injured list over the weekend, and an MRI on Monday revealed the moderate strain. Boone did not offer a specific timetable for Grisham's return, but it wouldn't be a surprise if he's held out through the All-Star break. Spencer Jones and Cody Bellinger will be tasked with holding down center field while Grisham is out.