The Jaguars placed Blue (ankle) on injured reserve Sunday, Ian Rapoport of NFL Network reports.
Blue had been spotted in a walking boot early last week due to the ankle injury, and will now have to sit out the first eight games of the season before he's eligible to return. Blue's emergence as the primary backup to Leonard Fournette was a positive sign for he and the team, but now that he's sidelined, the role likely will go to rookie Ryquell Armstead. Aside from the aforementioned players, recent acquisitions Devine Ozigbo and Tyler Ervin are the remaining running backs on the roster.