Ray was diagnosed with a Grade 2 oblique strain, Steve Gilbert of MLB.com reports.
Ray was placed on the 10-day disabled list Monday due to the injury. Manager Torey Lovullo said that it's unknown when Ray will be ready to return from the DL, so a timeframe will begin to take shape as his rehab gets underway. It remains to be seen who the Diamondbacks will call upon to replace Ray in the rotation, but Triple-A Reno starters Braden Shipley, Kris Medlen, Taylor Clarke and Troy Scribner are among the candidates who could join the big club.