Delgado was up to the challenge as he fanned Aramis Ramirez and got Jung Ho Kang to ground out to end the threat.
The move gives the D-backs 13 pitchers, including eight in the bullpen, which Hale believes is important given that Monday night marked the fourth game of a stretch of 21 games in 20 days.
"It just gives everybody else a break," Hale said. "We're being very careful with the whole bullpen making sure we don't burn anybody out."
Delgado suffered a sprained right ankle during a conditioning session prior to the July 28 game against the Mariners in Seattle.
He appeared in one game with Double-A Mobile during a brief rehab assignment and fanned two in a scoreless inning. Delgado also threw one inning for the team's entry in the Rookie-level Arizona League.
"I think it's ready now," Delgado said. "I've been feeling pretty good for the last week."
In 41 appearances in relief for the D-backs this year, Delgado is 4-3 with a 2.79 ERA, and he had a 0.66 ERA in his 12 outings prior to the injury.
"He's been throwing the ball great," Hale said. "I like using him in those middle innings to get out of trouble. He's been able to come in and stop the bleeding for us, so that's another reason we wanted him back. We're excited to have that bullpen back to full strength."
Romak was informed of the demotion following Sunday afternoon's 2-1 loss to the Braves in Atlanta. He started one game and appeared in five others, going 3-for-10 with a double.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.