In his first appearance in more than two years, Reynolds struck out two in a scoreless inning of relief during Sunday's 4-0 win over the Reds.
After relying on the bullpen for a substantial amount of innings during the series -- including 6 2/3 innings in Saturday night's 11-7 win over the Reds -- D-backs manager Chip Hale said a move was needed to bring up a fresh arm.
"Gives Reynolds a shot to come up here. He's been pitching multiple innings with them," Hale said. "He's been pitching matchups against lefties so ,it gives us some versatility, and a guy who's been here and has some experience."
Hale added that he's not sure how long Reynolds will remain with the D-backs, stating it's a "day-to-day thing" and "just see how fresh we are after the game today and see where we go from there."
Reynolds was 3-6 with a 5.58 ERA in 50 innings across 45 appearances with Reno this season. He gave up three runs on four hits across 1 2/3 innings to pick up a loss in his last appearance on Wednesday against Oklahoma City.
He is 5-5 with a 3.58 ERA in 196 career appearances. Before getting hurt in 2013, he was on pace for potentially his best season with an 0-2 record, but career-best 1.98 ERA in 30 appearances.
Hessler made his Major League debut earlier this month on Aug. 8 against the Reds. He is 0-1 with a 15.19 ERA over 5 1/3 innings in eight appearances with the D-backs.
"Obviously, we wanted to get a fresh arm up here and felt like he needed a chance to go back, breathe a little bit and get back on track," Hale said. "We really like his stuff and just wasn't able to have much success after his first few outings."
Robert Bondy is an associate reporter for MLB.com.