Valbuena has been on the disabled list retroactive to Aug. 3, while Sweeney has been out since the end of June. Baker, recovering from Tommy John surgery, has not appeared in a game this season.
The right-hander made two starts for Class A Advanced Daytona (six hits, two earned runs, two strikeouts, two walks in 6 1/3 innings) and three for Kane County, where he's struggled, allowing 13 runs on 17 hits and six walks in 8 2/3 innings, with five strikeouts.
Joey Nowak is a reporter for MLB.com. Follow him on Twitter at @joeynowak. This story was not subject to the approval of Major League Baseball or its clubs.