Capps, who has worked on getting his fastball down in the zone and improving his command, changed up his delivery with the Zephyrs after recording a 3.60 ERA in 10 innings out of the bullpen during Spring Training.
"I was just trying to get back to what I naturally do instead of trying to just pitch like somebody else wanted me to," said Capps, who learned of his promotion at 10 p.m. on Tuesday and flew from New Orleans to Atlanta at 6 a.m. on Wednesday.
"It's kind of more like just getting to the natural delivery and letting the arm flow, because I was fighting myself a little bit, trying to get a little too over the top when I'm a little bit of a lower-arm slot guy."
Manager Mike Redmond has not decided what role the right-hander would play in the bullpen, but he is eager to use Capps, whom Miami acquired on Dec. 11 in a trade for Logan Morrison. Redmond said it was the "perfect time" to promote him.
Capps, 23, went 3-3 with a 5.49 ERA in 53 appearances out of the Mariners' bullpen last season, and he owns a 5.04 ERA in 84 career big league innings over two seasons with Seattle.
"He's got a big arm," Redmond said. "We loved his arm, and it was just a matter of he hasn't really pitched that long, that many years. It was just a matter of him figuring out his delivery again."
Caminero, 26, took his first career loss on Monday, when he surrendered a walk-off homer to Evan Gattis in the 10th inning of a 4-2 loss to the Braves. Caminero was recalled from New Orleans on April 9 to replace right-handed starter Jacob Turner, whom Miami placed on the 15-day disabled list with a right shoulder sprain.
Caminero has posted a 13.50 ERA (seven earned runs in 4 2/3 innings) in five appearances out of the Miami bullpen this season.
Joe Morgan is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.