Who will replace Chase Anderson in the Rotation?

Jul 18, 2015; Phoenix, AZ, USA; Arizona Diamondbacks starting pitcher Josh Collmenter (55) throws in the sixth inning against the San Francisco Giants at Chase Field. Mandatory Credit: Matt Kartozian-USA TODAY Sports
Here’s the most simple move. One that would require no roster movement at all. After spending the past few years as a productive fringe starter/reliever in the bullpen, Collmenter was given the reigns of the rotation was the Dbacks Opening Day starter in 2015. In early June, Collmenter relinquished his spot in the rotation due to poor performances.
After his last start on June 7th, Collmenter had a record of 3-6 and his ERA was 5.24. Collmenter received mercy and was just demoted to the bullpen. He did show glimpses of brilliance early in the season, having two scoreless 8+ inning outings. In the bullpen, Collmenter has allowed 2 runs in 11.2 innings (1.54 ERA) and has been scoreless in his last 8 innings. Collmenter has to be the favorite to return to the rotation.