Swarmer isn't starting Sunday's game against the Cardinals and will move to a relief role, Jordan Bastian of MLB.com reports.
Swarmer allowed five runs (four earned) over four innings during his last start Tuesday and lined up for his next turn through the rotation Sunday, but the Cubs will instead pitch Alec Mills. Swarmer posted a 5.84 ERA and 24:10 K:BB in 24.2 innings over five starts, but manager David Ross said the team now wants to see how the right-hander looks out of the bullpen.