Peterson allowed one run on three hits and three walks over four innings in Sunday's win against the Giants. He struck out three and did not factor in the decision.
The southpaw also hit a batter and uncorked two wild pitches, but Peterson was able to avoid significant damage in a short outing that lasted only 61 pitches (35 strikes). He was demoted to Triple-A Syracuse in May after posting a terrible 8.08 ERA through 39 innings. The 27-year-old has coughed up just one run over 10 innings since returning to the MLB level, lowering his season ERA to 6.61. Peterson will likely stay in the rotation for another start, which is currently lined up to be in San Diego, but after the All-Star break he figures to hand his spot off to Jose Quintana (ribs).