Santos (biceps) fired a scoreless sixth inning in Triple-A Tacoma's extra-inning loss to Oklahoma City on Tuesday, allowing two walks and recording a strikeout.
The right-hander threw 21 pitches overall in a laborious inning, but the silver lining to his control issues was the fact his arm got a good test. Santos has now made two appearances with the Rainiers of an inning apiece, and the Mariners may determine he only needs another turn or two before being deemed ready for activation.