The White Sox announced this morning that they’re in agreement with left-hander Sean Newcomb on a one-year deal that guarantees the southpaw $4.5MM this morning. Will Sammon of The Athletic reports that Newcomb “will at least get the chance to start” for Chicago. Lefty Ryan Rolison was designated for assignment to make room for Newcomb on the 40-man roster. Newcomb is a client of Tidal Sports Group.
Newcomb, 32, was a first-round pick by the Angels back in 2012 and spent years as a consensus top-100 prospect in the minors. The lefty made his big league debut with Atlanta back in 2017 after previously coming over as part of the Andrelton Simmons trade. He spent the first two seasons of his career as a rotation piece, with a 4.06 ERA (103 ERA+) and a 4.16 FIP that gave him the look of a decent back-end starter. Unfortunately, in 2019 early season struggles led to him being demoted to Triple-A and moved into a bullpen role upon his return. He started four games for the Braves in 2020 but struggled badly across those starts as well, and ultimately did not start another game for the team before being designated for assignment by the club.
The lefty was traded to the Cubs shortly after his DFA and moved to the bullpen for the club, but struggled to put things together over the next few seasons. He pitched to an atrocious 6.61 ERA in 47 2/3 innings of work at the major league level between the Cubs and A’s over the next three seasons, held back primarily by a whopping 15.0% walk rate. Back in January, Newcomb latched on with the Red Sox on a minor league deal and found a path back to a big league rotation job between a strong performance in Spring Training coupled with injuries to rotation pieces like Lucas Giolito and Brayan Bello that kept them off the Opening Day roster.
Newcomb’s performance once added to the rotation as a mixed bag. He made five starts for the Red Sox and posted a lackluster 4.43 ERA, but did so with strong peripherals. He struck out 25.7% of his opponents while walking 10.5%. After moving to the bullpen, he posted a much stronger 3.38 ERA in seven relief outings for Boston, though his strikeout rate cratered during those outings. That led the Red Sox to designate him for assignment in late May, and he found himself traded back to the A’s shortly thereafter.
The lefty remained with the Athletics for the remainder of the 2025 season and did extremely well for himself with the club. In a full-time relief role for the A’s, Newcomb pitched to a dazzling 1.75 ERA with a 2.69 FIP in 51 1/3 innings of work. That excellent performance was backed up by strong peripherals, as he struck out 24.9% of his opponents, walked just 7.0%, and posted a strong 48.9% ground ball rate. His 3.22 SIERA in West Sacramento would be good for 44th among relievers with at least 50 innings of work last year if separated from his time in Boston. He’d also rank fifth by ERA and 18th by FIP.
That performance is more than strong enough to justify offering Newcomb a solid one-year guarantee to be a lefty bullpen arm, and the 32-year-old likely could have landed a similar dollar amount from a more competitive team for 2026 based on contracts offered to comparable lefties this offseason like Caleb Thielbar, who re-upped with the Cubs on a $5MM guarantee earlier this month. With that said, those contenders would have presumably wanted to keep Newcomb in a full-time bullpen role. The White Sox, by contrast, don’t have expectations of contention headed into 2026 and therefore can afford to offer Newcomb the opportunity to earn a rotation spot this spring.
Fellow offseason signing Anthony Kay figures to join Shane Smith and Davis Martin in the front three rotation spots for the White Sox this year. That leaves Newcomb to compete with players like Sean Burke, Jonathan Cannon, and Chris Murphy for the last two spots in the club’s rotation. It wouldn’t be a shock to see Newcomb land that role, though it’s certainly possible that he could also be used in a late-inning role given that the Sox bullpen has only Mike Vasil and Jordan Leasure as leverage options at the moment, with Tyler Gilbert as the top lefty option.
As for Rolison, the southpaw was claimed off waivers from Atlanta earlier this month. Rolison made his MLB debut as a member of the Rockies this past year, but struggled badly to the tune of a 7.02 ERA in 42 1/3 innings of work at the big league level for Colorado this year. The lefty will now be put through the waiver wire again, unless the Sox work out a deal involving Rolison before then. Should he pass through waivers unclaimed, Rolison figures to be outrighted to Triple-A as non-roster depth for Chicago headed into the 2026 season.