The Mariners placed Kowar on the 60-day injured list Sunday after he was diagnosed with a torn UCL in his right elbow. He'll undergo Tommy John surgery next Friday in Dallas, Daniel Kramer of MLB.com reports.
After experiencing arm soreness early last week, Kowar was sent in for tests Friday, at which point the UCL damage was detected. The 27-year-old will miss the entirety of the upcoming campaign and likely the first couple months of 2025 as well. Kowar, whom Seattle acquired from Atlanta in December, was expected to handle a low-leverage role out of the Mariners bullpen.