PHILADELPHIA -- Mark Vientos struggled in 2023. He didn’t make the Mets’ 2024 Opening Day roster in March. And he didn’t stick in the big leagues until after he played 31 games in Triple-A to start the season.

But it’s what happens in October that matters, and the 24-year-old third baseman has been delivering as the Mets’ No. 2 hitter in the National League Division Series against the Phillies.

Playing in his first postseason, Vientos mashed two home runs at Citizens Bank Park in the Mets’ 7-6 loss on Sunday.

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“Enough can’t be said about Vientos,” said veteran left fielder Brandon Nimmo. “He is really blossoming into a heck of a player, and [he] is a force with his power and someone that you always have to worry about. Just so proud of him. I thought that was a huge moment, both of those home runs. They were spectacular.”

Vientos went 3-for-4 with one double, two homers, two runs scored, four RBIs, one walk and one strikeout in Game 2. He tallied 10 total bases, becoming the third-youngest player to record 10-plus total bases in a postseason game. At 24 years and 300 days, Vientos is older than only Carlos Correa (21 years and 20 days, Game 4 of the 2015 ALDS) and Manny Ramirez (23 years and 134 days, Game 2 of the 1995 ALCS).

Vientos is also the third-youngest player in Mets history to tally multiple extra-base hits in a postseason game. Michael Conforto (22 years and 244 days) hit two home runs in Game 4 of the 2015 World Series against the Royals, and David Wright (23 years and 288 days) collected two doubles against the Dodgers in Game 1 of the 2006 NLDS.

“I think he plays above his age. I think he’s very poised and calm and knows the moments and takes advantage of it,” said right-handed reliever Reed Garrett. “He’s amazing, amazing, amazing. He’s having such a great season. All year he’s done it, so we’re lucky he’s on our team.”

Vientos’ first home run of the day came on a first-pitch changeup from Phillies starting left-hander Cristopher Sánchez in the third inning. Vientos joined Braves first baseman Matt Olson (Aug. 29) as the only two players this season to homer off a Sánchez changeup. His Statcast-projected 354-foot, two-run dinger to right field put the Mets on the board first.

“I was trying to get a pitch up in the zone and drive it through the gaps,” Vientos said. “I’m just focused on what I’m doing in that present moment.”

Vientos didn’t let the enormity of the moment overwhelm him when he stepped to the plate in front of 45,679 fans with the Mets trailing, 6-4, with one out and one on in the ninth inning of a back-and-forth thriller. He worked a full count against left-hander Matt Strahm and sent a high 91.9 mph fastball a projected 392 feet to left-center field at 105.3 mph to even the score in the instant classic.

“He’s not afraid of the situation,” Nimmo said. “He understands that failure is a part of this game, but he doesn’t let that dictate how he’s going to plan for the game and how he’s going to attack it. He goes and he gives it his best shot every single time. Sometimes it works out, and sometimes it doesn’t. But you’re really seeing him play without any fear, and it’s just really refreshing to see at such a young age.”

Vientos is slashing .400/.429/.750 with a 1.179 OPS in his first five career playoff contests. This, just one year after splitting his time between Triple-A Syracuse and New York last season. Vientos batted .211 with a .620 OPS in 65 Major League games in 2023, compared to .266 with an .838 OPS in 111 big league games this year.

He headed into the playoffs with the momentum of ranking third on the Mets in home runs (27) and fourth in hits (110), runs (58) and RBIs (71) this season.

“It's pretty cool, pretty cool,” Vientos said Friday. “It’s an honor just to be on the roster of a playoff team and living out a dream.”