Cubs Add Veteran Reliever Trent Thornton to Crowded Bullpen Mix

The Chicago Cubs have continued their methodical approach to building bullpen depth, agreeing to a minor-league contract with veteran right-hander Trent Thornton that includes a non-roster invitation to major league spring training. The move adds another experienced arm to an increasingly competitive relief picture.

The agreement was first reported publicly by Tread Athletics and later confirmed by longtime Chicago radio insider Bruce Levine. While the deal does not guarantee a roster spot, it gives Thornton a clear opportunity to compete for a role once camp opens.

Thornton, 32, enters the organization with seven seasons of major league experience and a recent track record of effectiveness in relief. The Cubs, who leaned heavily on internal competition last season, appear intent on recreating that formula once again.

For a team still searching for consistent bullpen production behind its established late-inning options, Thornton represents a low-risk addition with the potential for meaningful upside if healthy.

1. A Veteran Arm With a Proven Track Record

Thornton has appeared in 235 major league games between the Toronto Blue Jays and Seattle Mariners, compiling a 14–19 record with a 4.38 ERA across 401 innings. Over that span, he has struck out 379 hitters, providing steady if unspectacular production. His most consistent stretch came in Seattle, where he settled into a full-time relief role. From 2023 through 2025, Thornton logged 140 2/3 innings with a 3.65 ERA, striking out 130 batters across 127 appearances. While his numbers do not place him among elite relievers, Thornton has shown an ability to handle leverage situations and multi-inning assignments. That versatility could appeal to a Cubs staff that values flexibility throughout the bullpen. Thornton’s experience also gives him an edge in spring training competitions, particularly as Chicago weighs reliability against upside among its relief candidates.

2. Injury Recovery and Role Evolution

Thornton’s 2025 season was cut short on July 31 after he tore his left Achilles while covering first base on a ground ball against the Texas Rangers. The injury sidelined him for an estimated six to eight months and abruptly halted a season in which he was being used regularly out of Seattle’s bullpen. At the time of the injury, Thornton was 2–0 with a 4.68 ERA in 33 appearances. According to Tread Athletics, he is currently ahead of schedule in his rehabilitation and has already resumed throwing bullpen sessions. That progress puts him on track to be fully available for spring training, a critical factor in the Cubs’ decision to extend a non-roster invitation. Health will ultimately determine how much Thornton can factor into Chicago’s plans. Thornton originally reached the majors as a starter with Toronto, making 29 starts and logging 154 1/3 innings during his 2019 rookie season. After uneven results in the shortened 2020 season, he transitioned permanently to relief work beginning in 2021.

3. A Fit for the Cubs’ Bullpen Blueprint

The move to the bullpen revitalized Thornton’s career, particularly after he joined the Mariners. In 2023, he posted a 2.08 ERA over 26 innings, followed by a 3.61 ERA across 72 1/3 innings the next season, establishing himself as a dependable middle-relief option. During his time in Seattle, Thornton struck out 22.5% of opposing hitters while walking just 6.6%. He relied heavily on a mid-80s slider, which he threw more than half the time, while averaging 95.5 mph on his fastball during the 2024 season. His underlying profile — including a 39.7% ground-ball rate — aligns with the Cubs’ recent emphasis on strike-throwing relievers who can limit damage and handle varied roles. Those traits could help him stand out in camp. Thornton now joins a deep and crowded bullpen competition. The Cubs have added Phil Maton, Hunter Harvey, Jacob Webb, and Hoby Milner this offseason, while re-signing left-hander Caleb Thielbar. Additional minor-league signings include Charlie Barnes, Corbin Martin, Jeff Brigham, and Collin Snider.