The Red Sox have called up their top pitching prospect, 23-year-old left-hander Josh Tolle, from Triple-A to replace Sonny Gray who left his Monday start early due to a hamstring strain. The move comes as the Red Sox continue to reduce their deficit in their lineup. Tolle has not pitched since April 12 and is currently ranked as Boston's No. 1 prospect by MLB Pipeline. He will face right-hander Cam Schlittler in the upcoming series finale against the New York Yankees.