Diaz (elbow) was placed on the 15-day DL on Sunday, Rob Biertempfel of the Pittsburgh Tribune-Review reports.
Diaz was a likely candidate to start the season at Triple-A Indianapolis, but due his standing on the 40-man roster, the Pirates will be able to stash him on the 15-day DL until he's healthy once again. He figures to remain only an organizational depth option at catcher for the Pirates while Francisco Cervelli and Chris Stewart remain healthy.