White Sox GM Chris Getz didn’t sugarcoat it. Speaking on September 14, Getz said Luis Castillo‘s performance since arriving from Seattle has «trended in the wrong direction» — and that the results have been «surprising.» The numbers back him up completely.
In 29 innings with Chicago, Castillo has posted a 7.76 ERA and 1.79 WHIP — the worst marks of his career. That’s not a slump. That’s a full-blown problem, and it’s landing at the worst possible moment: the White Sox lead the AL Central over the Cleveland Guardians by just half a game with 22 games remaining.
What Getz Said — and What He Didn’t Have to
The quote came through ESPN’s Jesse Rogers, and it was unusually direct for a GM in the middle of a pennant race. Getz acknowledged the situation plainly and said the team needs to «find ways to improve it.» The tone wasn’t optimistic spin — it was a front-office leader who knows the plan hasn’t worked.
That makes the words hit harder when you remember what Chicago gave up to get Castillo at the August 2 deadline: Seranthony Domínguez, Nolan Jones, and catching prospect Boston Smith. The bet was that a three-time All-Star with a career 3.72 ERA could anchor a shaky rotation down the stretch. He’s done the opposite.
From Seven Straight Seasons Under 4.00 ERA to This
Castillo, a 33-year-old from Baní, Dominican Republic 🇩🇴, had posted a sub-4.00 ERA in seven consecutive seasons before 2026. He was already struggling in Seattle — 5.06 ERA in 99.2 innings with the Mariners — but nobody expected the wheels to come off further after the trade.
With Chicago, things have unraveled fast:
- He’s allowed 13 earned runs in his last 10.2 innings across three starts
- He’s failed to complete five innings in five of his seven appearances with the White Sox
- Opposing hitters are slashing .325/.379/.605 against him — an OPS approaching 1.000
- His four-seam fastball averaged just 92.6 mph in his September 13 start, well below his usual velocity
Chicago’s coaching staff identified mechanical issues — specifically problems with his leg drive and shoulder opening — and sent him to work in the bullpen on September 9 before returning him to the rotation. Castillo said he felt «very, very close» to fixing it. His numbers on September 13 in St. Louis said otherwise. Getz spoke the next morning.
The Math Is Unforgiving
The White Sox sat at 76-73 on September 14, leading the Guardians (76-74) by half a game. Twenty-two games left. The rotation was the exact reason Getz moved at the deadline, and Castillo was the centerpiece of that plan.
To be fair: Castillo’s struggles haven’t knocked Chicago out of first place. But when your biggest July investment is sitting in the 14th percentile in xERA across all of MLB according to Statcast, your margin for error in the final weeks of the season is essentially zero.
The Full 2026 Numbers
Castillo’s overall 2026 line across both Seattle and Chicago tells a complicated story — Statcast suggests he’s been somewhat unlucky, but not nearly enough to explain the results:
- 23 starts, 128.2 innings
- ERA: 5.67 · WHIP: 1.48
- 111 strikeouts, 43 walks (19.1% strikeout rate)
- xERA: 5.01 — the ERA Statcast says he deserved based on contact quality
- Four-seam fastball averaging 95.2 mph with 2,207 RPM spin rate
- Whiff rate: 23.8%
- Opponents batting .284 against him
- Exit velocity allowed: 89.8 mph
- Barrel rate allowed: 9.5%
- xERA: 14th percentile in MLB · xwOBA against: 14th percentile in MLB
He’s in the fourth year of a 5-year, $108 million contract. The real question facing Chicago right now isn’t whether Castillo can turn it around — it’s whether the White Sox can win the AL Central if he doesn’t.
