Nuno came in and threw 6 2/3 innings to spare the bullpen from being worn down.
"His changeup was better and he saved us, let's put it that way," D-backs manager Chip Hale said. "He saved us in that first game against the Nationals. He enabled us to be able to compete the next two days against them."
With Bradley coming off the disabled list, the D-backs wanted Nuno to go back to starting at Reno so that he could be prepared should the need arise again for a starter.
"Like I told him, we're a blister away from needing a fifth starter up here," Hale said.
• Veteran catcher Jarrod Saltalamacchia has joined Triple-A Reno after spending the past week in extended spring training.
The D-backs signed Saltalamacchia on May 7 after he was released by the Miami Marlins.
There is no timeline as to when Saltalamacchia might be called up.
"He's going to catch. He and Peter O'Brien are kind of splitting time there catching," Hale said. "[Reno manager Phil Nevin] and everybody who's there will evaluate where Salty is and whether he's ready to come here and help us win."
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.