Diaz will not be available out of the bullpen for Thursday's series opener against the Yankees, Greg Johns of MLB.com reports.
The hard-throwing righty has pitched five of the last six days, so manager Scott Servais will give him the night off Thursday. The recently acquired David Phelps will not report to the team until Friday, so Tony Zych or Steve Cishek would be the primary closing options should a save situation arise.