No corresponding moves will be announced until Saturday, but the club figures to add left-handed reliever David Rollins as well as another reliever and possibly a temporary position player to fill out the 25-man roster.
Elias will be replaced in the rotation by Hisashi Iwakuma, though Iwakuma won't start until Monday when the club faces the Tigers to open a seven-game homestand leading up to the All-Star break.
Thus a position player could be brought up for the weekend in Oakland to provide manager Lloyd McClendon an extra weapon until Iwakuma is activated off the disabled list on Monday.
Iwakuma was one of the American League's top right-handed starters the past three years (37-19, 2.97 ERA in 77 starts), but struggled in three outings this year (0-1, 6.61 ERA) before being shut down with a strained lat muscle on April 21. Elias went 4-6 with a 4.27 ERA in 13 starts as his replacement.
"Elias has thrown the ball extremely well," McClendon said. "He probably doesn't deserve to be going down, but we can only carry so many guys on the roster. He has options. These things are tough sometimes, but that's the way it goes."
The bullpen moves are another matter. Wilhelmsen is being sent down after not pitching well for the last few weeks. The big right-hander has allowed nine runs on 11 hits and six walks over 6 2/3 innings in his last seven appearances and has allowed 11 of 12 inherited runners to score this season.
After posting a 2.27 ERA in 57 appearances in 2014, Wilhelmsen has a 4.68 ERA in 22 games this season.
"One thing I told Tommy is just go down and get your command back and get back to pitching off the fastball," McClendon said. "He just hasn't done that his last 12-13 outings."
Nuno was acquired along with outfielder Mark Trumbo from the D-backs on June 3. The left-hander has a 2.53 ERA with three runs and 10 hits allowed in 10 2/3 innings in nine appearances for Seattle, but becomes the odd-man out with the return of Rollins from an 80-game PED suspension.
As a Rule 5 Draft pick from the Astros, Rollins must either be added to the 25-man roster on Saturday or be put on waivers and -- if not claimed by another club -- be offered back to Houston for $25,000. Rollins pitched extremely well in Spring Training and seemed on the verge of earning a roster berth out of camp until he was suspended for testing positive for an anabolic steroid.
He spent the early part of the season working out at the team's facility in Peoria, Ariz., and has pitched extremely well (9 1/3 scoreless innings over seven appearances with seven hits, one walk and eight strikeouts) over the past two weeks for Triple-A Tacoma.