"He has to cool off and the inflammation has to cool down before we consider getting him to throw again," Reds manager Bryan Price said. "I would be more optimistic [Iglesias could return] after the midpoint of the month than I would saying by the 15th or by the time we go on the road that he's ready to go. I don't know if I can safely say that right now. We're going to want him to be able to play catch, play long toss, throw a bullpen before thinking about putting him back into a ballgame."
Tim Adleman took Iglesias' spot in the rotation and delivered six innings of two-run ball against the Pirates in his big league debut and is scheduled to start again Friday vs. the Brewers.
Iglesias, who is 1-1 with a 3.49 ERA in five starts this season, is pleased with the progress in his non-throwing rehab program.
"Everything is going well, everything is going fine," Iglesias said via translator Julio Morillo. "I haven't felt the pinch because I haven't thrown yet. I just focus right now on being stronger and recovering and come back soon as possible."
During his rookie season in 2015, Iglesias did not pitch after Sept. 13 because of right shoulder fatigue. That prompted the Reds to have him undergo a special offseason shoulder strengthening program which stretched into the start of Spring Training. Iglesias, 26, got a late start in Cactus League action but repeatedly said he felt great throughout.
The latest shoulder setback was not necessarily a sign that the efforts Iglesias made to strengthen his shoulder failed.
"It's an impingement. Having had a shoulder impingement myself, that can be anything from a pitch where you get in a bad position and you injure it and it gets inflamed," Price said. "You try to pitch with it anyway, and it gets sore. It's a lot easier to trigger when you've already done it once. That's my experience with it. Once you've had an impingement, until you get the inflammation out, it's really difficult to do anything from a throwing perspective."
Despite his setback, Iglesias felt optimistic about resuming his season soon.
"I don't feel frustrated about it," Iglesias said. "This happened early in the season, and I just hope to come back stronger in order to help the team to win."
Mark Sheldon has covered the Reds for MLB.com since 2006, and previously covered the Twins from 2001-05. Read his blog, Mark My Word, follow him on Twitter @m_sheldon and Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.