The Athletics signed Alexander to a minor-league contract Nov. 15.
Alexander signed a minor-league contract with the Red Sox on Feb. 20.
Alexander cleared waivers and was outrighted to Triple-A Nashville on Monday, Curt Hogg of the Milwaukee Journal Sentinel reports.
The Brewers reinstated Alexander (shoulder) from the 60-day injured list Saturday and optioned him to Triple-A Nashville, Adam McCalvy of MLB.com reports.
Alexander (shoulder) is beginning a rehab assignment Friday in the Arizona Complex League, Adam McCalvy of MLB.com reports.
Alexander was placed on the 60-day injured list on Saturday.
Alexander will be sidelined until around late May due to right shoulder soreness, Adam McCalvy of MLB.com reports.
Alexander was recalled from Triple-A Nashville on Tuesday, Adam McCalvy of MLB.com reports.
The Brewers optioned Alexander to Triple-A Nashville on Wednesday.
Alexander allowed three runs on six hits and a walk while striking out five in 3.2 innings during Sunday's loss to the Yankees. He didn't factor into the decision.