In a low-risk move aimed at bolstering bullpen depth, the Chicago Cubs have acquired left-handed reliever Tom Cosgrove from the San Diego Padres in exchange for cash considerations. To make room on the 40-man roster, Chicago designated right-hander Caleb Kilian for assignment.
Cosgrove, 28, was recently DFA’d by San Diego following a rough spring and slow start to the Triple-A season. The southpaw gave up seven runs in just 5 1/3 innings during Spring Training and has allowed three earned runs in four appearances for Triple-A El Paso this year. Still, his prior success makes him a worthwhile reclamation project for the Cubs, especially with a minor league option still in play.
The Cubs immediately optioned Cosgrove to Triple-A Iowa, where he’ll try to regain the form that made him a standout rookie in 2023. That year, Cosgrove posted a 1.75 ERA across 54 appearances for the Padres, holding hitters to a .173 batting average and showing strong ability to suppress hard contact. His strikeout and walk numbers weren’t elite, but his effectiveness against hitters from both sides of the plate made him a valuable piece of the Padres bullpen.
The Cubs acquire southpaw reliever for bullpen depth
Things unraveled last season, however. Cosgrove posted an 11.66 ERA over 18 big league outings in 2024, and his velocity and swing-and-miss numbers dipped noticeably. He finished the year mostly in Triple-A, where he carried a 4.85 ERA with a solid 26.8% strikeout rate. While his recent performance has been underwhelming, the Cubs are betting a change of scenery might help him get back on track.
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Kilian, 27, is the corresponding roster casualty. Once viewed as a key return piece in the 2021 Kris Bryant trade with the Giants, Kilian has struggled to establish himself in the big leagues. Over eight MLB appearances (five starts), he has pitched to a 9.22 ERA in 27 1/3 innings, walking 20 and striking out just 21. His lone outing at Triple-A Iowa this year didn’t go much better—he gave up six runs in just 2 1/3 innings, surrendering three home runs.
While Kilian still possesses a mid-to-high-90s fastball and a varied pitch mix, his inability to consistently miss bats or command the zone has kept him from sticking at the MLB level. Given his past prospect pedigree and the remaining option year, it's likely another club could claim him off waivers. If not, the Cubs could outright him to Iowa and retain him as organizational depth.
This trade amounts to a simple change-of-scenery swap: two pitchers in their late 20s, both out of options after this year, both in need of a spark. For the Cubs, Cosgrove brings much-needed lefty depth with a strong track record—albeit a short-lived one—at the major league level. And for a bullpen that has lacked consistency, any upside is welcome.
It also subtly marks the end of an era. If Kilian is lost on waivers or released, the Cubs will have parted ways with the entire return from the Kris Bryant trade within a matter of months.
