David Peterson's Mets Career Ends: A Story of Promise, Progress, and the Perpetual Search for More

For six-plus seasons, David Peterson was baseball's version of that refrigerator in your basement that somehow kept working despite every indication that it shouldn't.

Not flashy.

Not dominant.

Not entirely reliable.

But somehow always there.

That chapter officially ended last night when the Mets traded the longest-tenured player on their roster to the Chicago Cubs in exchange for first baseman prospect Cole Mathis, one of Chicago's top 15 prospects.

For Peterson, it closes the book on a Mets career that can best be described as a seven-year exercise in trying to answer one question:

Who exactly was David Peterson?

The answer, unfortunately, changed depending on which month you asked.

When the Mets selected Peterson with the 20th overall pick in the 2017 draft, the hope was obvious. A big left-hander with a quality slider and the pedigree of a first-round pick, Peterson projected as the type of durable mid-rotation starter every organization covets.

What followed was a career filled with flashes.

His major league debut during the shortened 2020 season looked promising. Peterson went 6-2 with a 3.44 ERA across 49.2 innings and appeared to be another successful piece of the Mets' growing young core.

Then came the inconsistency.

In 2021 his ERA ballooned to 5.54.

In 2022 he bounced back to a respectable 3.83.

In 2023 he regressed again to 5.03.

Every time it appeared Peterson had solved the puzzle, another piece would go missing.

By the time the 2023 season ended, many Mets fans had already made up their minds. Peterson was useful depth, a swingman, an occasional starter—but probably not much more.

Then came the hip surgery.

And suddenly everything changed.

For much of 2024, Peterson looked like the pitcher the Mets thought they were drafting seven years earlier.

His delivery was cleaner.

His command improved.

The sinker had life.

The slider missed bats.

Most importantly, he finally looked comfortable attacking hitters instead of surviving them.

Peterson finished 2024 with a 10-3 record, a 2.90 ERA, and 2.9 WAR over 121 innings. Opponents hit just .250 against him, and for the first time in his career he looked less like a back-end starter and more like a legitimate rotation anchor.

The transformation carried into the first half of 2025.

Through July 26, Peterson owned a sparkling 2.83 ERA and a 7-4 record. He had thrown at least six innings in 18 of his first 20 starts and authored the first complete-game shutout of his career against Washington on June 11.

The reward was an All-Star selection.

Finally.

After years of teasing potential, David Peterson had become the pitcher Mets fans always hoped he could be.

Then baseball reminded everyone why it remains the cruelest game on earth.

Starting in August of 2025, Peterson's season began to unravel.

Over his final 10 starts of the year, he posted a 5.93 ERA.

There were warning signs everywhere.

Atlanta knocked him around for six runs in just 3.1 innings.

Miami tagged him for eight runs in two innings.

The final week of the season produced a pair of rough outings against San Diego and Chicago that pushed his ERA from an excellent 3.18 at the end of August to 4.22 by season's end.

The underlying metrics suggested trouble was brewing.

While Peterson finished 2025 with a solid 9-6 record and 168.2 innings, his 3.48 FIP significantly outperformed his actual results. His walk rate remained elevated and his margin for error was razor thin.

Unfortunately, 2026 turned those warning signs into flashing red lights.

The numbers from 2026 tell a difficult story.

In 16 appearances, Peterson posted a 6.09 ERA and a negative WAR.

The underlying metrics weren't much kinder.

His Baseball Savant profile looked more like a warning label than a scouting report.

* Pitching Run Value: -12

* Fastball Run Value: -9

* xERA: 4.83

* Opponents expected batting average: .269

* Strikeout rate: just 19.7%

* Hard-hit rate: 42.2%

The ground balls were still there. His 52.9% ground-ball rate ranked among the better marks in baseball.

Everything else wasn't.

Hitters were squaring up the fastball.

The strikeouts disappeared.

The walks remained.

And the confidence that defined the previous two seasons vanished.

By June, Peterson had become a pitcher searching for answers while trying to stay on the major league roster.

Here's what makes this move remarkable.

The Mets didn't have to designate Peterson for assignment.

In fact, they managed to turn a struggling pending free agent , 30-year-old starter with a 6.09 ERA and declining underlying metrics into a legitimate prospect.

That deserves recognition.

Had Peterson remained in New York much longer, there was a realistic possibility his roster spot would have become increasingly difficult to justify.

Instead, David Stearns found a trade partner and extracted value from an asset that appeared to be rapidly depreciating.

Who Is Cole Mathis?

The return is 22-year-old first baseman Cole Mathis, a player whose scouting reports read like they were written by three different evaluators who all watched different games.

The good news?

Everyone agrees he can hit.

Mathis owns a smooth right-handed swing, controls the strike zone well, and consistently produces quality at-bats. Scouts project average hit and power tools with enough strength to eventually produce 20-home-run seasons.

Before being drafted in the second round by Chicago in 2024, Mathis was one of college baseball's premier two-way players at the College of Charleston. As a sophomore he posted a 1.014 OPS while simultaneously recording a 3.45 ERA on the mound.

Yes, he was doing both.

Apparently he was unaware that most people struggle to do one thing well.

The concerns are defensive.

While the Cubs initially announced him as a third baseman, most evaluators believe first base is his eventual home. His arm is strong enough for third, but the range and athleticism probably aren't.

In other words, if he's going to make it, the bat will have to carry him.

The encouraging part is that he hasn't really had an opportunity to show what that bat can do professionally.

Tommy John surgery and subsequent elbow issues limited his development and restricted him to just 29 Single-A games before reaching the Arizona Fall League.

The Cubs still viewed him as one of their better prospects despite the lack of professional at-bats.

The Mets are betting that health unlocks the player scouts saw in Charleston and on Cape Cod.

David Peterson leaves the Mets having accumulated 40 wins, 690.2 innings, a 4.31 ERA, and 6.0 career WAR.

Those numbers won't earn a plaque in Cooperstown.

They probably won't earn a Mets Hall of Fame plaque either.

But they do tell the story of a pitcher who spent seven years fighting to become more than he was.

For one glorious stretch after hip surgery, he succeeded.

For a few months in 2024 and the first half of 2025, Peterson looked like the dependable left-handed starter the Mets had envisioned all along.

Unfortunately, baseball careers are judged by the entire body of work, not the highlight reel.

Peterson's Mets tenure ultimately became a story of untapped potential, intermittent brilliance, and the frustrating reality that some players spend their careers convincing you they're one adjustment away from becoming stars.

As for the Mets, they turned a struggling veteran into a prospect with upside.

Whether Cole Mathis becomes a major league contributor remains to be seen.

But on a day when David Peterson's long and winding Mets journey came to an end, the organization managed to get something many thought impossible.

Value.

And considering where Peterson's trajectory was heading, that may be the most impressive accomplishment of all.