Curtis was designated for assignment by the Mariners on Monday.
Curtis was cut loose to clear room on the roster for Jacob Hannemann and Seth Frankoff, who were both claimed off waivers from the Cubs. The 25-year-old appeared in three games for the big club this season, allowing three unearned while striking out two in 4.2 innings of work. While he doesn't have much major-league experience, he compiled a respectable 3.51 ERA and 60 strikeouts in 51.1 innings for Double-A Arkansas this season, so it's possible he'll draw some interest on waivers.