Mariners' Sam Carlson: Undergoes TJ surgery

Carlson (elbow) underwent season-ending Tommy John surgery Monday and could be sidelined through the 2019 campaign, Greg Johns of MLB.com reports.

The 19-year-old Carlson, a 2017 second-round pick, was only able to pitch three innings across two appearances in the Arizona Rookie League last season before experiencing soreness in his right elbow. The issue persisted into this spring, which prevented Carlson from seeing any game action. He got as far as throwing a bullpen session in late May, but he wasn't able to progress beyond that point. Given the timing of the surgery, it appears likely that Carlson's next realistic opportunity of taking the mound will come in the winter of 2019 or spring of 2020.