Zac Rosscup is a left-handed relief pitcher. This is the main feature that recommended him to the Mariners. (The other being, of course, that he was once a member of the Tampa Bay Rays organization.)
Released by the Los Angeles Dodgers in November, he signed with the Mariners in December and joined Roenis Elias to form the lefty contingent in the bullpen. With Elías potentially making spot starts and long relief appearances to ease Yusei Kikuchi into the major leagues, Rosscup is suddenly the go-to for disposing of pesky left-handed batters in the late innings.