Irvin will no longer start Sunday's game against the Angels as previously scheduled and is instead expected to pitch behind opener Riley Cornelio, Mark Zuckerman of NatsJournal.com reports.
It will be the first appearance out of the bullpen in Irvin's major-league career. After missing all of June and most of July due to a shoulder injury, the 29-year-old has gone 0-5 with a 5.90 ERA, 1.51 WHIP and 32:20 K:BB over 39.2 frames in eight starts since coming off the IL.