Muller elected free agency Saturday.

The Athletics outrighted Muller to Triple-A Las Vegas on Friday, Martin Gallegos of MLB.com reports.

The Athletics selected Muller's contract from Triple-A Las Vegas on Wednesday.

The Athletics outrighted Muller to Triple-A Las Vegas after he cleared waivers Wednesday.

The Athletics designated Muller for assignment Tuesday.

The Athletics reinstated Muller (shoulder) from the 15-day injured list Sunday.

Muller (shoulder) started Triple-A Las Vegas' loss to Oklahoma City on Tuesday, allowing two earned runs on two hits and a walk over 2.2 innings. He struck out five.

Muller (shoulder) allowed an earned run on two hits and two walks over 1.1 innings in a relief appearance for Triple-A Las Vegas against Sacramento on Friday. He struck out one.

Muller (shoulder) fired a scoreless inning during Triple-A Las Vegas' win over Sacramento on Tuesday, allowing a hit and recording a strikeout.

Muller (shoulder) will begin a rehab assignment at Triple-A Las Vegas on Tuesday, Martin Gallegos of MLB.com reports.