Manager Kevin Cash said McClanahan underwent an MRI on Wednesday which confirmed the diagnosis of a shoulder impingement, and the left-hander is scheduled to receive a cortisone injection, Marc Topkin of the Tampa Bay Times reports.
Cash added it's possible the 25-year-old will spend only the 15-day minimum on the injured list, but the return timeline will depend how the shoulder responds to the injection. Regardless, McClanahan will be unavailable until at least mid-September, which is major blow to both the Rays and fantasy managers.