Wagner was optioned to Triple-A Round Rock on Monday, TR Sullivan of MLB.com reports.
Wagner hasn't necessarily impressed this spring, allowing six runs on 13 hits across eight innings. He pitched well in the majors and minors in 2016, but an undisclosed injury shut his season down early and eventually led to him being subjected to waivers. He'll head back to Triple-A in 2017, where the 25-year-old will look to work his way back to the big leagues.