2 NY Mets players whose late collapse is a red flag moving forward, 2 whose isn't

David Peterson’s second half likely isn’t sustainable

David Peterson followed up his very promising 2024 season by making the All-Star game in 2025. By the end of July, Peterson had a 2.83 ERA, 3.38 FIP, and 1.25 WHIP over 121 innings pitched. Peterson only had a 20.1% K%, but a solid 8.2% walk rate and an outstanding 0.52 HR/9 ratio. Peterson avoided quality contact well, as evidenced by his home run rate, along with his 5.9% barrel percentage. 

But the rest of the season did not go well for Peterson. He had a 7.74 ERA while walking 10.9% of opponents. His HR/9 also got slightly worse, rising to 0.76, and his barrel rate climbed to 7.5%. Peterson’s ERA on the season, which once sat below 3.00, ended at 4.22. However, that’s about where the negatives end for Peterson’s second half. There were far more positives than his surface numbers might suggest.

Peterson’s 4.29 SIERA and 3.88 xFIP were much better than his ERA, which was approaching 8.00. Plus, they weren’t that much worse than the 4.00 SIERA and 3.66 xFIP he had through the first four months of his season, and almost identical to the 3.88 xFIP and 4.20 SIERA he had from his first start of 2024, through the end of July 2025. His .366 batting average on balls in play and 53.1% left on base rate are both indicators of some bad luck at play, compared to the .313 BABIP and 72.7% LOB rate of his career. Peterson’s stuff and execution got better, with an 89 Stuff+ and 101 Location+ through the end of July, and a 92 Stuff+ and 105 Location+ in August and September. He was fooling batters more frequently as well. Batters swung outside the zone 28.5% of the time with a 22% whiff rate when facing Peterson in his first 20 starts of the year. They had a 32.1% out-of-zone swing rate and 22.2% whiff rate during August and September vs Peterson.

Plus, what sample size is more reliable? The 41 starts and 242 innings where Peterson had a 2.86 ERA, or the ten starts and 47.2 innings where he struggled? Peterson’s final months of the 2025 season should be one of the Mets’ lesser concerns heading into the offseason. Sure, him struggling was a reason the Mets fell off down the line, but it’s nothing the Mets should fret over this offseason.