Nunez had developed into a premium setup man, and his 1.71 ERA and 3-1 record in 21 games have been missed.
"There was a domino effect," said manager Trey Hillman, "because you tend to go with the experience of getting the job done, and especially with the guys who have been effective, and, primarily, that was Ron Mahay and [Ramon] Ramirez. We upped the ante on Jimmy [Gobble] a bit, and so far, it hasn't been too successful for Jimmy."
Gobble gave up a grand slam that raised his ERA to 8.10 on Wednesday in a loss to Texas. Trying to work things out, he took the unusual step of pitching batting practice to teammates on Friday.
Ever-reliable closer Joakim Soria is OK now but a sore hindquarter made him unavailable for a couple of days recently.
"And that, in some shape or form for the last week, has been part of the restructuring as well," Hillman noted.
Ramirez, Mahay and Yasuhiko Yabuta are being summoned more frequently as Hillman works to fill the gap left by Nunez. He sees great improvement in Yabuta, despite the game-ending homer he allowed Friday night.
"I think that five out of seven days we utilized him, out of necessity, and that's what you're going to get with a Japanese pitcher. They'll take the ball any time," Hillman said. "Every day he's going to tell you, 'I'm OK, I'm going to take the ball for you.' Sometimes, it's a little overuse and I'm responsible for that."
Overused or not, Yabuta had a 1.26 ERA in 14 outings since May 9.
In Saturday's 12-3 win, recently-arrived Jeff Fulchino and Carlos Rosa, making his big-league debut, each threw a perfect inning.
"Hopefully, they can be part of that bullpen and we can ease them into a situation. Yabuta, I think, is going to continue to get better," Hillman said.
Nunez (strained right lat) and John Bale (broken left hand) are staying behind at the Surprise, Ariz., camp to continue rehabbing their injuries. They are not expected to be ready to return until around the All-Star break.
"You've got to be careful with Noonie simply because of where the injury was [below and behind his armpit] and the violence of his delivery," Hillman said. "If he wasn't a max-effort guy, he might have the opportunity to come back a little sooner."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.