Cubs Patch Battered Rotation by Acquiring Left-Hander David Peterson from Mets

With their starting rotation in shambles, the Chicago Cubs made a move Thursday to shore up the staff, acquiring left-handed pitcher David Peterson from the New York Mets in exchange for minor league infielder Cole Mathis.

Filling a Glaring Need

The trade was announced before Thursday's series finale between the two clubs at Citi Field, coming just one day after the Cubs placed both Ben Brown and Edward Cabrera on the 15-day injured list. Brown is dealing with a neck strain, while Cabrera is sidelined with a left hamstring strain. Those two join a growing list of Chicago starters on the shelf — Jameson Taillon, Cade Horton, and Justin Steele are also currently on the injured list — leaving the Cubs with precious few healthy arms in the rotation.

Who Is David Peterson?

Peterson, 30, was a first-round pick by the Mets in the 2017 MLB Draft out of the University of Oregon. He made his major league debut in 2020, going 6-2 with a 3.44 ERA, and appeared to turn a corner last season when he earned an NL All-Star selection, threw his first career shutout, and posted an 8-5 record with a 3.18 ERA over his first 24 starts.

However, Peterson struggled badly to close out last year — posting a 10.36 ERA over his final six starts — and that rough stretch has carried into 2026. He enters the trade with a 3-6 record and a 6.09 ERA across eight starts and eight relief appearances, including a bruising 10.97 ERA in three June appearances alone. His most recent outing saw him allow four earned runs and six hits over just four innings in a loss to the Philadelphia Phillies.

Why the Cubs See Upside

Despite the troubling numbers, there is reason for optimism in Chicago. Peterson carries a 52.9% groundball rate — a profile that could play well behind the Cubs' defensive infield, widely regarded as one of the best in baseball. The contrast with his former club is stark: the Mets committed six errors — all in the infield — during Wednesday night's loss to Chicago in a doubleheader nightcap, a game that no doubt underscored the defensive difference between the two organizations.

A change of scenery has revived struggling pitchers before, and the Cubs will be counting on exactly that.

What Chicago Gave Up

In return, New York receives Cole Mathis, a 22-year-old second-round pick from the 2024 amateur draft. Despite his youth, Mathis has impressed at the minor league level this season, batting .272 with 10 home runs and 39 RBIs in just 39 games across two stops. The Cubs also designated right-hander Yosver Zulueta for assignment in a corresponding roster move.

Outlook

Peterson is eligible for free agency at the end of the season, making this a low-risk, high-need acquisition for Chicago rather than a long-term commitment. With so many rotation pieces on the shelf, the Cubs needed a warm and capable body, and Peterson — at his best — has shown he can be a quality major league starter. Whether a fresh environment and a reliable defense behind him can unlock that version of Peterson again remains to be seen, but the Cubs are banking on it.