On the verge of the trade deadline, it is likely that he'll be snapped off of waivers by any of the numerous teams looking for lefty depth or he'll find a major-league job soon after the deadline dust settles.
The Cardinals planned to have Mayers complete his 30-day rehab assignment at Class AAA Memphis and then make a roster move Friday to bring him back from Triple-A. Mayers is out of options, and once his rehab assignment ran out of time the Cardinals' choices were limited. They could trade him, move him back to the injured list, or promote him.