The Cubs announced that Peterson will be moved to the bullpen after Edward Cabrera (hamstring) was reinstated from the 15-day injured list Sunday, Patrick Mooney of The Athletic reports.
Rather than shifting to a six-man rotation, manager Craig Counsell will send Peterson to the bullpen to provide the club with a multi-inning arm to replace Javier Assad, who was optioned to Triple-A Iowa on Sunday. After a disastrous run with the Mets to begin the season, Peterson had pitched more credibly since being acquired by the Cubs in late June. Over eight starts with Chicago, Peterson has gone 4-1 with a 4.19 ERA, 1.37 WHIP and 31:16 K:BB across 43 innings.