The Giants placed McDonald on the 15-day injured list Tuesday with a right elbow strain, Evan Webeck of the California Post reports.
Analysis:McDonald made an early exit from his start Monday after suffering an injury while warming up for the fifth inning, and he'll now officially have to miss a few turns through the rotation. Tristan Beck will come up from Triple-A Sacramento to give the Giants some extra bullpen depth while the team sorts out its rotation plans.
