Peterson will be shifted to the bullpen, Will Sammon of The Athletic reports.
With the return of Jose Quintana from the 60-day injured list, Peterson will lose his spot in the rotation and be pushed into a multi-inning relief role. The 27-year-old southpaw has been hit around consistently this season and holds a 6.46 ERA and 1.64 WHIP through 54.1 frames across 11 starts.