Castro (shoulder) has been pulled back from his throwing program, Alex Weiner of Arizona Sports reports.
It's unclear exactly when Castro was taken off the program, but he's "been shut down for a couple of days," per Diamondbacks manager Torey Lovullo. The right-hander had been cruising through the regimen, throwing out to 90, 110 and 120 feet when he felt discomfort on the top of the shoulder. Lovullo said Castro just needs a bit more rest and a second opinion is not needed at this time.