White Sox reliever Jordan Leasure to miss all of 2027 after UCL surgery, timeline points to Spring Training ’28

The Chicago White Sox received a significant blow to their bullpen plans for 2027 when they announced that right-handed reliever Jordan Leasure underwent surgery to repair a torn UCL. The team announcement, relayed by Scott Merkin of, said the procedure took place a few weeks before the announcement and that Leasure is expected to miss the entire 2027 season.

The timeline attached to the surgery matters as much as the injury itself. According to the report, Leasure is expected to be ready for the beginning of Spring Training ’28. In practical roster terms, that places him on a two-year runway away from game action, which is why the situation is being framed as an extended absence rather than a mid-season recovery.

Leasure, 28, has been part of the relief corps as a bullpen option for outs in late innings. With a torn UCL requiring surgery, teams typically plan around a full rehabilitation cycle, including a gradual return to throwing and bullpen preparation before any regular-season usage. For a club, that means another bullpen slot likely has to be covered by other internal arms or external reinforcements for 2027.

For Chicago, the decision to disclose surgery and an expected return window also affects how the White Sox can balance near-term performance goals with long-term roster development. A reliever facing a lengthy absence often changes the way a bullpen is constructed, because modern bullpen usage is built around predictable availability and role clarity, particularly for late-inning situations.

There is also a broader baseball context to the announcement. UCL surgeries have become common enough across Major League Baseball that clubs have established a playbook for rehab, but pitchers still vary in how quickly they regain command and pitch effectiveness after recovery. Even when a player is “expected to be ready” in spring, the first few outings can be tightly managed as the arm re-adapts to higher stress.

What to watch next is how Chicago structures the 2027 bullpen around Leasure’s absence. The most immediate indicators will be whether the White Sox accelerate the progression of other relievers, shift role assignments for existing bullpen members, or add depth to cover high-leverage innings. For Leasure personally, spring 2028 will be the key checkpoint, with his progression likely measured by his ability to handle throwing volume, bullpen sessions, and controlled game appearances.