With top prospect Tyler Skaggs already moved to the club's Minor League camp, Delgado and Corbin are the last remaining pitchers in contention for the back-end starting rotation spot.
While Corbin surrendered two runs on just three singles on Friday, Delgado couldn't keep opposing hitters inside the park, giving up three home runs.
"They are good hitters; maybe I didn't hit the right spot, but they just hit the ball," said Delgado, who allowed just three runs total in his previous 11 innings of work. "I don't blame too much [on] the pitches, they were just putting good swings on them."
Delgado also struggled with his command at times, walking four batters. Before Saturday, the right-hander had only issued two walks all spring.
"I respect those guys, so it was hard," Delgado said. "After two balls, I was trying to be too careful and stay around the corners. That was my mistake, maybe."
Delgado's outing could've been worse if it weren't for a few quality defensive plays behind him throughout the afternoon. Miguel Montero picked off a runner at third, Gerardo Parra threw out a Royals runner from right field and Aaron Hill made a nice snag in the hole to start a double play.
The final batter Delgado faced, Jeff Francoeur, hit a line drive up the middle off the pitcher's back, but he said he felt fine once the initial sting went away.
"Thank God, I'm OK," Delgado said. "It just hit me in the middle of my back."
If the D-backs want to, both Corbin and Delgado could get one more start in a Cactus League game before the club makes its decision.
Tyler Emerick is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.