Martin will start Friday's series opener against the Padres in San Diego, Nick Piecoro of the Arizona Republic reports.
Diamondbacks manager Torey Lovullo confirmed the assignment for Martin, who has not gotten off to a good start with the team. The 25-year-old right-hander has an 8.62 ERA and 2.04 WHIP over four outings (two starts). Martin believes he's trying to be too fine with his pitches, particularly with two strikes. "I think I'm picking the zone a little bit too much," he said. "I would say that at some point I try to be too perfect with two strikes and that's when I'm losing guys." Opposing batters are hitting .281/.395/.563 off Martin with two strikes, while the league average in those situations is .161/.237/.259.