After reshaping the bullpen with Seranthony Domínguez, the White Sox are now monitoring left-hander Cionel Pérez — a once-dominant reliever whose recent struggles may be tied more to usage than ability.
The Chicago White Sox wasted no time using some of the money they saved from trading Luis Robert Jr.’s contract to address a clear bullpen need.
Robert is owed $20 million in 2026, but the White Sox offloaded his entire contract to the New York Mets in a trade last week, opting for a lesser prospect return in exchange for financial flexibility.
Was that necessary? I’ve argued against it. But what’s done is done, and the best course of action for the White Sox moving forward is repurposing that money to fill other holes on the roster.
They took a step in the right direction with a two-year, $20 million contract for Seranthony Domínguez — who will likely be the White Sox’s closer this season.
And while it’s not the most pressing need still on the board — White Sox fans are crying out for additions in the outfield and the starting rotation — more bullpen help could be on the way.
According to reporter Francys Romero, the White Sox are among the teams showing continued interest in left-handed reliever Cionel Pérez.
The 29-year-old pitcher held a workout on Saturday in Tampa, drawing scouts from roughly 20 MLB teams.
It was his second workout in recent weeks, and the White Sox were in attendance for both.
Per Romero, Pérez reached 98 mph with his fastball, his slider sat at 86 mph, and his spin rates were above average.
Pérez pitched in 19 games for the Baltimore Orioles in 2025, struggling to an 8.31 ERA before being designated for assignment and sent down in May. He did not return to the big leagues after his demotion and continued to struggle at Triple-A Norfolk, posting a 6.85 ERA last season.
Still, Pérez is not far removed from MLB success — you could even call it MLB dominance without much resistance from me.
Back in 2022, he went 7–1 with a 1.40 ERA across 66 appearances for the Orioles. That team took a major step forward, setting the stage for Baltimore’s 101-win season in 2023.
That following year, Pérez was productive again, posting a respectable 3.54 ERA in 65 outings.
At first glance, Cionel Pérez’s collapse is confusing. When you dig into the advanced metrics, many of the usual red flags simply aren’t there. His average exit velocity, chase rate, and whiff rate in 2025 weren’t drastically different from what he posted during his dominant 2022 season. In fact, in some areas — including barrel rate and ground-ball rate — Pérez actually improved.
And yet, the results couldn’t have been more different.
The clearest explanation lies not in the quality of his stuff, but in how it was deployed.
In 2022, Pérez leaned heavily on his four-seam fastball, throwing it nearly half the time (45 percent usage), pairing it with a slurve that gave him strong vertical separation. Hitters had to cover two different planes, and that contrast — fastballs up, breaking balls down — helped create deception.
By 2025, that identity had flipped. Pérez threw his sinker more than 40 percent of the time, while the four-seamer became his fourth-most-used pitch at just 11 percent. That shift first appeared in 2023 and stuck, even as the results deteriorated.
On paper, the change made sense. The sinker produced ground balls and limited barrels, fitting neatly into Baltimore’s broader pitching philosophy that emphasizes contact management and arm-side movement.
But sinkers are far less forgiving than four-seamers.
They demand precise command and are extremely sensitive to small lapses in location or release point. Even a slight miss can turn a ground-ball pitch into something that lives on a hitter’s bat path. Pérez didn’t need to be wildly off for the sinker-heavy approach to fail — he just needed to be slightly imperfect.
The result was a pitcher who still looked fine in isolated metrics, but lost his margin for error. Without the four-seam fastball establishing a different visual plane, hitters were able to sit on similar movement patterns and react more comfortably.
Pérez wasn’t necessarily getting hit harder — he was getting hit at worse times and in worse spots.
The contrast that once masked his mistakes disappeared, leaving him exposed. Add in some unfortunate batted ball luck, and you've got an inflated ERA and few answers for what went wrong.
The Orioles bet that a sinker-first version of Pérez could be more sustainable, even if it was less explosive. He fit the exact profile of a pitcher they’d push in that direction: a lefty with mid-to-upper-90s velocity, natural arm-side run, and limited vertical ride on his four-seamer.
Instead, it required a level of precision that proved difficult to maintain.
With recent workouts flashing that upper-90s fastball, it will be interesting to see if a team attempts to restore the 29-year-old to his old pitch mix and channel some of the success he had in 2022 before the change.
During that season, Pérez allowed just a .536 opposing OPS to left-handed hitters. He was the ultimate matchup arm for Brandon Hyde to deploy out of the bullpen — and even beyond that year, his career left-on-left splits remain favorable.
The White Sox have a mix of left-handed arms competing for MLB roster spots in 2026, but very little is decided or set in stone. There could be as many as three bullpen spots available, one of which could belong to Sean Newcomb if he ultimately misses out on the starting rotation.
Pérez could be a strong addition to that group — another arm for Brian Bannister to tinker with in camp. He’s likely seeking an MLB deal, but a minor league contract with a Spring Training invite may ultimately get it done.
We know the White Sox value upside, and they’re not afraid to bet on player development.
Keep an eye on Pérez landing with a team in the coming weeks.