Clarke was optioned to Triple-A Reno following Sunday's game against the Nationals.
Clarke didn't factor into the decision Sunday, allowing three runs on four hits (two home runs) and a walk while striking out three in 5.2 innings. Despite the serviceable outing, it wasn't enough for the right-hander to keep hold of a starting gig with Zac Gallen -- who was acquired from the Marlins in exchange for Jazz Chisholm last week -- set to make his debut for Arizona on Wednesday. Clarke owns a lackluster 5.46 ERA, 1.42 WHIP and 48:22 K:BB in 62.2 big-league innings this season.