NEW YORK -- Following the Mets’ mistake-filled doubleheader sweep to the Cubs on Wednesday, the club made a trade on Thursday to send left-hander David Peterson -- the longest-tenured player with the team -- to Chicago for first baseman/DH prospect Cole Mathis.
Peterson was an All-Star in 2025, but struggled as part of a beleaguered New York rotation this season, holding a 6.09 ERA with a 3-6 record in 16 appearances (8 starts). In his last appearance for the Mets, he allowed five runs (four earned) in four innings, taking the loss on Sunday against the Phillies.
Before Thursday’s series finale against the Cubs, manager Carlos Mendoza shared that president of baseball operations David Stearns made the move to give the Mets greater roster flexibility in the pitching department. But despite the pragmatic nature of the move, it was impossible for Mendoza to ignore the emotional implications of trading away a player like Peterson.
TRADE DETAILS
Cubs get: LHP David Peterson
Mets get: 1B/DH Cole Matthis (Cubs' No. 13 prospect)
“It’s a tough one, because you obviously understand this is a business,” Mendoza said. “But, especially from my end, I had a really good relationship with Petey. This is a guy that will come into the office and have coffee, and just talk about life. We’ve been together since I took the job, and we’ve been through the ups and downs. [I've] seen him have success, make the All-Star [Game]; [I've] seen him struggle, a lot, and how he handled it.
“But it got to a point where we needed flexibility with the roster. Talking to David [Stearns], we already have [Kodai Senga] in the 'pen, and just continue to have starters in the bullpen. It’s just not going to be sustainable. There was an opportunity to make a deal, and we’ll move forward.”
Peterson was selected by the Mets with the No. 20 pick in the 2017 MLB Draft, and he had spent his entire professional career with the organization. After making his debut in 2020, he enjoyed a modicum of success during his first four seasons, until he had offseason surgery on his left hip in November 2023. The realignment contributed to the best stretch of his career from 2024-25, when Peterson went 10-3 with a 2.90 ERA in his first year back, then followed it up with an All-Star campaign in ‘25, when he threw the first shutout of his career.
After a scoreless, 5 1/3-inning showing in his first start of the season, Peterson was unable to find his footing in his starts, and he accepted a role to piggyback out of the bullpen in April. He oscillated between starting and relief all the way until his last three appearances in June, when he allowed 14 runs (13 earned) in 10 2/3 innings. But according to Mendoza, there was no indication that Peterson was traded because of any reaction to his volatile role.
“He’s a professional,” Mendoza said. “He was always willing to do whatever the team needed. Whether it was as a bullpen guy, as a piggyback, as a starter -- he’s done everything for us. He represents this team on and off the field in a quality way.”
Zach Thornton, the Mets’ No. 12 prospect, is likely to take Peterson’s spot in the rotation and start Friday’s series opener against the Phillies, according to Mendoza. Christian Scott, who’s been sidelined with a hip impingement since June 15, is likely to return to start on Saturday, helping to settle the club’s immediate rotation plans.
Mathis became the No. 14 prospect in the Mets’ organization. This season, he’s slashing .272/.396/.585 with a .981 OPS in 39 games across Single-A and High-A. While he’s only played 68 games since being taken in the second round of the 2024 Draft -- he underwent Tommy John surgery shortly after being selected -- scouts are encouraged about his potential as a promising power bat from the right side. In just 14 games with Single-A Myrtle Beach this year, he crushed seven home runs with a 1.204 OPS before getting moved up a level.