TRADE: Desperate Cubs Pick Up Left-Handed Starter David Peterson from Mets

[Matthew Trueblood]

Image courtesy of © Kyle Ross-Imagn Images

It's not about finding playoff-caliber starters right now. It's not about building a bridge to a long-term winner, either. The Cubs simply have games to play this weekend, and too few healthy starting pitchers to fill the slots on their schedule. Feeling around in the dark, they scooped up the first thing they could grab hold of, acquiring David Peterson from the Mets in a late-night trade Wednesday. 

Jeff Passan of ESPN was first with the news, on Twitter. A source with knowledge of the deal confirmed that the teams have agreed to terms.

Peterson, 30, will be a free agent at season's end. He's running a hideous 6.09 ERA this season, in stark contrast with last year, when he made the National League All-Star team. However, below the surface, he's been almost the same guy in both years. In fact, per Baseball Prospectus, his DRA- for 2026 (90) is lower than the mark he put up last year (97).

Nothing Peterson throws misses bats very well, so he runs a below-average strikeout rate. However, his best pitch is a worm-killer of a sinker, with which he induces lots of ground balls. He's a fine fit for the Cubs, who not only have a good defense to put behind him but badly need a hurler who can keep the ball in the park more often.

With that inability to pile up strikeouts, Peterson will slide into the back end even of a atrociously depleted Cubs rotation, but he gives them stability and upside there. His fastball shapes fit the Cubs' predilections well. This deal could pave the way for the team to keep Peterson around relatively cheaply beyond this year, despite his impending free agency, and for now, it rescues them from needing to install the empty husk of Vince Velazquez in their rotation for any significant length of time.

According to Will Sammon of The Athletic, minor-leaguer Cole Mathis will go to New York in the trade. 

Mathis, 22, was a second-round pick in 2024 and has put up good numbers this year at High-A South Bend. That it took until his second full year in pro ball to get out of Myrtle Beach after playing high-level college ball, however, says something about his long-term outlook. It's a small price to pay for Peterson, but because of his contract status and his struggles this year, Peterson was extremely available. For now, this stabilizes the Cubs rotation.

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[Justspittintruths]

Why not just bring up Will Sanders and give him a shot? I’m not going to cry over losing Cole Mathis, but it’s still a complete waste of a recent second round draft pick. And anyone who wants to claim we need someone to eat innings can stuff it where their proctologist earns his money….pretty damn sure that there are plenty of guys at Triple-A or even Double-A who can get beat like a rented mule to the tune of a 6 plus ERA.

[Jason Ross]

42 minutes ago, Justspittintruths said:

Why not just bring up Will Sanders and give him a shot? I’m not going to cry over losing Cole Mathis, but it’s still a complete waste of a recent second round draft pick. And anyone who wants to claim we need someone to eat innings can stuff it where their proctologist earns his money….pretty damn sure that there are plenty of guys at Triple-A or even Double-A who can get beat like a rented mule to the tune of a 6 plus ERA.

David Peterson career: 22.6 K%, 9.8 BB%, 4.31 ERA, 3.91 FIP, 3.86 xFIP
David Peterson 2025: 20.7 K%, 9.0 BB%, 4.22 ERA, 3.48 FP, 3.72 FIP 
David Peterson 2026: 19.7 K%, 9.4 BB%, 6.09 ERA, 3.85 FIP, 4.05 xFIP

What's the only number that stands out from his career line (over the course of 690 IP, and 123 starts), his 2025 season (Peterson made the 2025 all-star team) and his 2026? It's his ERA in this year only. He's an extreme ground ball pitcher. Did you watch game-2 of the DH yesterday? The Mets infield made 6-errors on their own. They're a -8 OAA as an infield. His LOB% this season is 60%. That is unsustainably low. It's obvious why his ERA is 6.00. It's not really a David Peterson issue.

No one should claim Peterson as a star, because he isn't. But he's also a pitcher highly dependent on infield defense and the Mets have been abysmal in this category. The Cubs are a +19 OAA on the infield, which is one of the very, very best. We should expect his ERA with the Cubs to be around the xFIP marker, if not a bit better considering his defense is going to help him out in this regards.

Don't be a single issue voter and just attach yourself to the ERA. The story of David Peterson is deeper than his 6.00 ERA. 

[Justspittintruths]

• Definition: An earned run is any run that scores without the aid of an error or a passed ball. 

So, the Mets porous infield contributes to his inflated earned run average even though errors do NOT contribute to ERA. Gotcha chief. I'm not gonna attempt to argue with that kind of genius. All bow down to king Jason, if you don't you might get banned...or accused of being Bombadil. 

[Justspittintruths]

I'm just going to go ahead and delete my bookmark to your site buddy boy. Hey, maybe you can write another article about how the Cubs need to trade the barely turned 21 shortstop at double-A who has 13 homers through 60 games and is on a close to 30-30 pace while competently playing the most important position on the diamond. 

[Justspittintruths]

Douche

[mul21]

13 minutes ago, Justspittintruths said:

 

• Definition: An earned run is any run that scores without the aid of an error or a passed ball. 

So, the Mets porous infield contributes to his inflated earned run average even though errors do NOT contribute to ERA. Gotcha chief. I'm not gonna attempt to argue with that kind of genius. All bow down to king Jason, if you don't you might get banned...or accused of being Bombadil. 

So you're saying bad defenders don't affect a pitcher's ERA in a negative way?  You realize there's more than errors being used to determine how good a defender is right?  We have all kinds of tools now like outs above average and defensive runs saved, not to mention some of the older stuff like range factor.  There's a reason guys like Dansby and Nico have solid WAR numbers every year in spite of their less than star level offensive performances.  This whole take is just dumb and uninformed.

[sneakypower]

why is this thread basically

[We Got The Whole 9]

47 minutes ago, Justspittintruths said:

 

• Definition: An earned run is any run that scores without the aid of an error or a passed ball. 

So, the Mets porous infield contributes to his inflated earned run average even though errors do NOT contribute to ERA. Gotcha chief. I'm not gonna attempt to argue with that kind of genius. All bow down to king Jason, if you don't you might get banned...or accused of being Bombadil. 

Dickhead.

 

Don't you think a bad infield fails to convert opportunities into outs? That is what OOA measures. What he said is accurate and you shouldn't be so confident in your attacks. His numbers look worse than they are because the defense has performed poorly. The Cubs have an excellent defense that should convert a much higher% of opportunities into outs.

[Andy]

52 minutes ago, sneakypower said:

why is this thread basically

Gotta give it to that guy, I don't think anyone has landed on my ignore list so quickly

[Jason Ross]

1 hour ago, Justspittintruths said:

 

• Definition: An earned run is any run that scores without the aid of an error or a passed ball. 

So, the Mets porous infield contributes to his inflated earned run average even though errors do NOT contribute to ERA. Gotcha chief. I'm not gonna attempt to argue with that kind of genius. All bow down to king Jason, if you don't you might get banned...or accused of being Bombadil. 

When we see a two point differential in ERA and xFIP something is going on. For Peterson, it seems directly tied to bad luck, bad variance and bad defense. Why? Everything else seems to lineup with what he's been doing before. As a pitcher who doesn't make his own outs with swings, but forces outs with the defense, he's much more affected by these things. It's why he's a less valuable pitcher on the surface, but also why a good infield defense can polish him up and make him look better. For the Cubs it's a cheap way to add an average starting pitcher into a rotation that needs some baseline. 

And to address it; I do know what an unearned run is. Bringing up the six infield errors was an anecdote of how bad they are. The -8 OAA is evidence beyond anecdote. They don't make plays they should overall. They're just a bad infield defense for a pitcher who relies on their defense a ton.

We can be better than to look at his ERA and scream from a mountain top that he sucks. We can also be better than to bring up "what about isms" and other, non related issues, such as Jefferson Rojas (whom I like as prospect very much and still ranked him #1 in my most recent too-20).