Alexander agreed to a minor-league contract with the Athletics on Thursday that includes an invitation to spring training, Jane Lee of MLB.com reports.
The 24-year-old lefty split 2018 between Double-A and Triple-A in the Tigers' organization, producing a 4.44 ERA in 140 combined innings. Alexander will get some exposure to the major-league coaching staff to start camp, though it's unlikely that he breaks camp in the majors given that he has yet to pitch above Double-A in his professional career.