Martinez was optioned to Triple-A Las Vegas on Saturday, Matt Kawahara of the San Francisco Chronicle reports.
Martinez will head to Las Vegas after posting a 2.84 ERA and 1.42 WHIP with six strikeouts over 6.1 innings in five appearances during his second stint with Oakland this season. The 26-year-old will likely get another shot with the Athletics this summer, but for now, Hogan Harris was recalled from Triple-A and will serve as the bulk relief pitcher following opener Austin Pruitt versus the Astros on Saturday. Meanwhile, the team's official site reports Martinez will work as a starter -- his projected long-term role in the majors -- with the Aviators after primarily operating in multi-inning relief out of necessity during his just-concluded big-league stint.