Martinez was optioned to Triple-A Round Rock on Wednesday, Stefan Stevenson of the Fort Worth Star-Telegram reports.
Martinez was unable to secure a long-relief role after getting lit up to the tune of an 8.66 ERA and 1.87 WHIP in 17.2 innings during spring training. He'll likely slot into the rotation at Round Rock for the time being and could reemerge as a swingman for the Rangers later in the season if injuries thin the pitching ranks.