Mariners Sign Zac Rosscup

The Mariners announced Thursday that they’ve signed left-handed reliever Zac Rosscup to a one-year, Major League contract. The team’s 40-man roster is now up to a total of 38 players.

“When healthy, Zac has swing-and-miss stuff, which has translated at all levels,” general manager Jerry Dipoto said in a statement accompanying today’s announcement. “We look forward to seeing what he can do with good health and real opportunity.”

Rosscup, 30, has indeed demonstrated proficiency in missing bats throughout his career, averaging 11 strikeouts per nine innings in the minors and averaging 11.9 K/9 in 65 2/3 frames at the MLB level. He’s also posted a strong 14.2 percent swinging-strike rate in his MLB career, and though he’s totaled just 18 innings over the past two seasons, those 2017-18 campaigns have been particularly interesting. Rosscup has dramatically increased the usage of his slider in that time, resulting in an eye-catching 30-to-4 K/BB ratio in that time. He’s pushed his swinging-strike rate beyond the 18 percent threshold and his opponents’ chase rate past 37 percent in that small sample of work.

Of course, as Dipoto alluded to, the real question with Rosscup is one of health. Over the past four seasons he’s missed time due to blister issues, a calf injury and multiple instances of shoulder inflammation — one of which resulted in surgery that cost him the entire 2016 season. Rosscup managed just 21 1/3 innings between the minor leagues and the majors this past season and 49 total innings the year prior.

Clearly, there’s ample injury risk as pertains to the lefty, but his ability to generate whiffs is, at the same time, genuinely intriguing. He also still has just three years, 164 days of Major League service time, meaning if he manages to carve out a role in the Seattle bullpen, he can be controlled through the 2021 season via the arbitration process. The Mariners’ bullpen has been thinned out dramatically this winter following trades of Edwin Diaz, James Pazos, Alex Colome and Juan Nicasio as well as the outrighting of Erasmo Ramirez and Nick Vincent. Given that mass exodus of relievers orchestrated by Dipoto & Co., Rosscup should have a fairly straightforward opportunity to prove himself a capable relief option.