"He's one of those guys that's going to have this opportunity to hold on to this spot for a while," said manager Bryan Price. "We know that [Amir] Garrett and Rookie were sent down for different reasons. Rookie's going down there to work on some things and make some aggressive changes to his game. Amir will be back here shortly, and we're just really giving him a chance to have a break. And Bonilla's a guy who's going to take advantage of an opportunity with Rookie going out to seize a spot in the rotation. If not for a short period, for an extended period, until we have other options."
Bonilla's start Saturday will be his first in the Majors since 2014 with Texas. Bonilla has appeared in one game this season, in which he allowed four runs in five relief innings.
The Reds had been stretching the righty out at Triple-A, where Bonilla owns a 5.61 ERA in five starts this season.
Davis, a rookie who made the team out of Spring Training, was optioned after pitching to a 7.58 ERA over five starts.