David Peterson had a strong relief appearance for the Mets against the Rockies, allowing two earned runs in four innings with six strikeouts. He now holds a 2.45 ERA as a reliever this season, compared to 8.10 as a starter.

The Mets are at an interesting crossroads with David Peterson.
After turning in another solid outing from the bullpen on Monday against the Colorado Rockies where he allowed two earned runs in four innings while striking out six, Peterson now has a 2.45 ERA in three appearances this season as a reliever. In five games as a starter, his ERA is 8.10.
So what should New York do with the left-hander?
Obviously, Peterson is more valuable to the Mets as a starting pitcher and if given the choice he would choose to be a starter. However, the numbers don't lie and so far this season Peterson has been more effective as a reliever.
"Thatās how I expect myself to pitch and thatās how I expect myself to attack hitters so thatās why it is disappointing when it has gone the other way a couple of times this year," Peterson said. "Great win today and one to build off of."
Actually, this isn't Peterson's first instance with pitching in relief. In his career he's made 18 relief appearances, albeit none since 2023 (although he did predominantly pitch out of the bullpen during New York's 2024 postseason run). Interestingly enough, Peterson's career regular season ERA as a reliever is 2.41 in 33.2 innings pitched. In the postseason? 3.14.
Pretty elite numbers.
As a starter, Peterson is 34-34 with a 4.33 ERA with his best year coming in 2024 when he had a 2.93 ERA in 21 starts after he began the season on the IL. Last year, after a terrific first half that made him an All-Star for the first time in his career, Peterson fell apart in the second half while reaching a career-high 168.2 innings pitched.
Despite the pretty noticeable difference in numbers between starting and relieving, as well as Peterson's inability to prove he can either stay healthy for an entire season or be effective the whole way through, the Mets and manager Carlos Mendoza still view the 30-year-old as a starter.
"Itās easy [to think Peterson pitches better in relief] because of three outings now where heās been really, really good, but I keep saying it, he's a starter," Mendoza said. "Heās very good when heās at his best and we saw it today. I think the key is attacking the strike zone. He pounded the strike zone today with everything."
David Peterson allowed two earned runs in four innings and struck out six batters against the Rockies.
Peterson has a 2.45 ERA in three relief appearances and an 8.10 ERA in five starts this season.
The Mets face a decision on whether to keep Peterson as a reliever, where he has been more effective, or return him to his preferred role as a starter.
Overall, Peterson has struggled as a starter but has shown effectiveness as a reliever, leading to questions about his future role with the Mets.
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The question becomes why hasn't Peterson pitched like he did on Monday or in his two other relief appearances this season when he starts a game?
When asked what the difference was between this relief outing and his last start where he allowed seven earned runs in 3.2 innings, Peterson pointed to examining his pitch-usage and finding that he wasn't using his slider enough, instead opting for other pitches like the curveball in similar spots.
"The slider is one of if not my best pitch and the curveball, overall, is towards the bottom of the list," he said. "So kinda switching that today and really being able to attack with the fastball and the slider off of it felt like gave us a really good chance."
If it's really that simple and Peterson can take what he did against the Rockies into his next start and beyond then the Mets will be ecstatic. If not, then the case for Peterson to remain in the bullpen grows.
Regardless of what New York decides to do with the left-hander, it's clear that Peterson plays an important role on the team.
"Heās too good of a pitcher and I know heās gonna continue to help us," Mendoza said.