The Rays designated Martin for assignment Thursday.
Martin will cede his spot on the 40-man roster to Jorge Mateo, who officially signed a major-league deal with the Rays on Thursday. The 25-year-old righty has given up four runs in 11.1 innings with Tampa Bay this year and owns a 3.09 ERA through 43.2 frames at Durham, though his inability to limit traffic may deter teams from picking him up via waivers.