"I think Bonilla would be more in the competition for bullpen length right now," Reds manager Bryan Price said on Tuesday. "It's just been a matter of performance so far to this point. With [Amir] Garrett and [Rookie] Davis and [Cody] Reed and [Sal] Romano, and [Luis] Castillo I think has been pretty impressive as well. [Robert] Stephenson has been a little bit of a mixed bag but has been competitive. I think there's a group of guys there that would be ahead of Bonilla at this point."
In four spring games through Monday, Bonilla has a 7.20 ERA, giving up four earned runs on nine hits with three walks, four strikeouts and one homer. Opposing batters are hitting .409.
The Reds claimed the 26-year-old right-hander off waivers from the Pirates just after camp opened in mid-February.
Bronson Arroyo and Tim Adleman are also in the hunt for rotation spots.
"I would say they would bump up above some of the guys I've mentioned simply because of past experience," Price said. "I don't mention Bronson a lot because we want to see him work up to the workload before. I think he's right in the middle of the competition, no question."
• Reds catcher Devin Mesoraco went to Minor League camp to hit and catch on Tuesday. Mesoraco, who debuted in a Cactus League game on Sunday, will be in the lineup on Wednesday against the Padres.
"Batting leadoff," Price noted. "We don't know the exact workload for Devin. We'll see how he gets through today, if it will be an increased workload of three or four innings. He's hitting leadoff with the hope he'll get a couple of at-bats. We'll see how it plays out."
• Non-roster first baseman/outfielder Sebastian Elizalde is due to return to camp shortly. Elizalde competed at the World Baseball Classic with Team Mexico, which was eliminated in the first round of pool play.
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.