SEATTLE -- Right-handed pitcher Sam Carlson, the Mariners' No. 3-ranked prospect per MLB Pipeline, has undergone Tommy John surgery on his right elbow and will be sidelined the remainder of this season and potentially all of 2019.
The 19-year-old from Minnesota was drafted in the second round by Seattle last year, but pitched just three innings over two appearances in the Arizona Rookie League in 2017 before being shut down with a sore elbow.
The arm continued to be a problem this spring and Carlson never got into any games this season. He threw a bullpen session in late May and there was hope at that time of getting him into extended spring training and eventually onto a Minor League club, but that never materialized.
With the typical recovery period of 12-15 months for Tommy John surgery to repair a torn ulnar collateral ligament, Carlson likely won't be ready to pitch competitively until the start of 2020.
The Mariners signed Carlson to a $2 million bonus after he dropped unexpectedly into the second round of the Draft last season, likely because of his option as a high school senior of attending the University of Florida. He immediately was installed as one of Seattle's top young pitching prospects due to his impressive showings on the summer showcase circuit, where he was throwing a mid-90s fastball and a promising slider and changeup.
But that promise will be put on hold now as Carlson goes through rehab, leaving recent first-round Draft pick Logan Gilbert out of Stetson University as the top young starting pitching prospect in the Mariners' Minor League system.
Gilbert has been assigned to Class A Short Season Everett, but the 21-year-old has yet to pitch and likely will be very limited this year as he's coming off a college season where he threw more than 100 innings.