Among the homegrown arms in the Mets rotation, Jonah Tong still has the most to prove.

Flashes of dominance have emerged from the 23-year-old rookie, but consistency is lacking. This was evident again Sunday, when the right-hander fell into an early hole, and his team never recovered in a 7-2 loss to the Phillies at Citi Field.

“I think I need to do a better job,” said Tong, who allowed two runs in the opening frame. “Especially, that first inning set the tone, but I feel like I competed well through it. But my job is to limit the damage and go out there and keep competing.”

Nolan McLean, Christian Scott and Zac Thornton have all performed at a high enough level to begin next season in the rotation. The wild card is Tong, who has pitched to a 4.21 ERA in six appearances this season. In three starts since his recall this month from Triple-A Syracuse, he’s pitched to a 4.60 ERA.

On Sunday, he allowed four earned runs on five hits and four walks over 4 ²/₃ innings, departing after 95 pitches. It followed a start against the Orioles in which he did not surrender an earned run over six innings.

“I don’t think he was far off today,” interim manager Andy Green said. “The changeup has been really good for him since he’s been up. He’s got a lot of strikeouts with it. … Even if he doesn’t have the greatest feel for that, we have got to find a way to reintroduce that and keep that a part of the mix. That pitch is very important for him.”

Green was asked about Tong’s chances of cracking the rotation to begin next season.

“He definitely has a chance,” Green said. “I think we have kind of painted the landscape for a lot of young guys that [the front office] is likely to go sign some people. We’ll have a lot of guys who have established themselves at that point in time, so the chance is heightened if he pitches really well, if his stuff gets better, if the strikes are there. I think all those things are possible for Jonah.”

New York Mets pitcher Jonah Tong (21) is knocked down by Philadelphia Phillies second baseman Bryson Stott (5) as he tags him at first base on a groundout to end the top of the first inning at Citi Field in Queens, N.Y., Sunday, Sept. 20, 2026. Robert Sabo for NY Post

The Mets, who split the four-game series, completed their 2026 home schedule at 36-45. They will play at Texas and Washington this week, with six games to conclude the season.

Tong walked Kyle Schwarber in the first inning and watched the Phillies DH score the first run on Luis Arraez’s sacrifice fly. Alec Bohm’s RBI single widened the Mets deficit to 2-0. Bryce Harper also singled in the inning.

Trea Turner’s RBI double in the third inning extended the Phillies lead to 3-0 after Schwarber walked leading off. Arraez’s RBI single gave the Phillies their fourth run.

“Some credit to Schwarber’s two walks,” Green said. “They weren’t walks where the pitcher has lost it. They are battle walks where he fouled off a number of pitches. The first and third [innings] started that way, and that’s where the runs came.”

New York Mets shortstop Francisco Lindor (12) strikes out looking during the third inning of a game against the Philadelphia Phillies at Citi Field in Queens, N.Y., Sunday, Sept. 20, 2026. Robert Sabo for NY Post

The Mets were overmatched by Cristopher Sánchez, a National League Cy Young Award candidate who allowed two earned runs on six hits over 6 ¹/₃ innings with six strikeouts. Sánchez began the day with a 7.5 bWAR this season — the highest among all pitchers.

Bo Bichette homered in the sixth for the first run against Sánchez. Brett Baty delivered a pinch-hit RBI single in the seventh that sliced the Phillies lead to 4-2.

Kodai Senga allowed three runs in the eighth and was removed after recording only one out. The right-hander’s appearance was his first since Tuesday, when he surrendered Pete Alonso’s 300th career homer — a game-tying blast in the ninth inning.