"We didn't want to send Smitty out, but the need today is for length in the bullpen and Smitty pitched four innings," Reds manager Bryan Price said. "We knew were going to give him at least two days off and he'll be ready to go when rosters are expanded and when the Triple-A season is over."
Smith was 2-1 with a 5.19 ERA that elevated when he allowed five earned runs on three homers over two innings vs. the Dodgers on Aug. 22.
Simon had previously pitched for Cincinnati on June 15 vs. the Braves and was placed on the DL with a strained right trapezius. During his rehab assignment with Louisville, he had a 4.80 ERA in five games and last pitched five innings with one run allowed on Wednesday.
"The last game was better as far as being sharp, being in the zone with good quality," Price said. "He got his pitch count up to over 80, so it gives us the flexibility heading into September where he could move his way into the rotation or we could spot start him if we wanted to or he could fill a need for us out of the bullpen as he did for us in 2012 and '13."
In the rotation, Brandon Finnegan is approaching his innings limit and Bailey is not assured of being ready to return for his next start on Saturday.
"I feel really good. All of my pitches were working good," Simon said before Monday's game.
Before the injury, Simon was demoted from the rotation to the bullpen amid deep struggles. After he gave up two runs on Monday, he is 2-7 with a 9.05 ERA in 14 games, including 11 starts. The Reds brought him back to the club during Spring Training on a one-year, $2 million contract.
"In the beginning of the season, it was bothering me there," Simon said of his shoulder area. "I couldn't throw my pitches down in the zone. That's why I got hit."
Catcher Tucker Barnhart, who has been out of the lineup since Friday with a right hand contusion, has shown improvement and reduced swelling. Barnhart's status remains day to day.
"I played catch today," Barnhart said. "I should hopefully be hitting in the next couple of days and hopefully playing before long."
Mark Sheldon has covered the Reds for MLB.com since 2006, and previously covered the Twins from 2001-05. 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.