On Sunday the Padres purchased Hynes' contract from Triple-A Tucson and optioned right-hander Brad Brach to Tucson.
Hynes made his Major League debut in the ninth inning of Sunday's 10-1 victory over the Giants, needing just seven pitches to dispense of the three hitters he faced.
Hynes went 2-0 with a 1.52 ERA in 41 games between Double-A San Antonio and Tucson after spending last season as a starter with the Padres' top Minor League affiliate.
In Spring Training the Padres asked Hynes -- a 31st-round Draft pick in 2007 out of Texas Tech -- to alter his delivery, having him lower his arm slot to three-quarters.
"It was just an experiment in the bullpen in camp. [The Padres] thought it would be more natural for me," Hynes said. "It felt pretty drastic at first."
But the change took hold, and Hynes had success with it almost immediately, recording a 0.73 ERA in San Antonio before earning a promotion. That success continued in Tucson, where he struck out 42 over 35 innings, with two walks.
"I was kind of surprised I felt as comfortable as I did with it," he said. "All the other coaches said that it looked good."
Manager Bud Black, who was familiar with Hynes from when he attended Major League Spring Training, was anxious to see Hynes.
"He got to the big leagues the old-fashioned way. He earned it through performance," Black said. "It's been a long way for Colt. These are good stories."
Brach appeared in four games since being recalled from Tucson on July 8. He allowed five hits and five runs (one earned) in one inning in a loss to the Giants on Friday.