ST. LOUIS -- Emotions were swirling for Harrison Bader as his spikes dug into the Busch Stadium batter’s box for the first time since last summer’s trade, and as the crowd reaction surged more loudly, Cardinals catcher Willson Contreras tapped him on the shoulder with his glove.

Contreras excused himself for a mound visit, and now the spotlight belonged fully to Bader, adoration and appreciation spilling from the occupants of thousands upon thousands of red seats. Reflecting following the Yankees’ 6-2 win over the Cardinals on Saturday evening, Bader said that the moment meant everything.

“That was really special,” Bader said. “Everybody that has cheered for me over the years, cheered me in that moment tonight; it means the absolute world to me. I put in a lot of years here, and the love and appreciation for that, it’s why I do it. Thank you to everybody for that. That was amazing.”

A fan favorite who was acquired by the Yankees last August in exchange for left-hander Jordan Montgomery, Bader doffed his batting helmet to acknowledge the sellout crowd of 44,846 before that first plate appearance, then lifted a sacrifice fly to give his current club its first lead of the day.

“I think it’s really important to be multi-dimensional when you’re trying to score runs,” Bader said. “When the offense is going really well, we’re hitting home runs and everything’s flowing, it’s really easy to go out there and produce runs. The game runs its course and you have to find ways to produce runs other ways, which we did tonight.”

The Yanks fell in Saturday’s opener, 11-4, as starter Luis Severino struggled in a contest that included more than two hours of rain delays.

“Tonight we were able to play a little bit of small ball,” said Isiah Kiner-Falefa, who reached base four times and scored on Jose Trevino’s ninth-inning safety squeeze. “Our pitching did well. Our bullpen has been awesome this year so far. It was nice to split the doubleheader today.”

New York opted to piece together the nightcap as a bullpen game, beginning with opener Ian Hamilton, who surrendered a leadoff homer to Lars Nootbaar.

Ron Marinaccio recorded five outs on his 28th birthday and Michael King served as the bulk reliever, tossing a season-high 3 1/3 innings of scoreless, one-hit ball.

“Obviously, I love getting outs and putting up zeros,” King said. “But there were pitches that I didn’t feel great on, and then there were ones where I’m like, ‘Ooh, I’ve got to replicate that.’ When I’m rolling, I’m feeling great on every pitch, and so I just want to replicate that every time out.”

Because Wandy Peralta, Tommy Kahnle and Clay Holmes all pitched scoreless frames, the Yankees lauded the complete group, awarding the team’s championship belt to the whole bullpen.

King said that Kahnle was tapped to speak on behalf of the group, calling Kahnle’s brief speech, “A very fun atmosphere after a long day. Very much-needed high energy.”

“They all love the competition; they’re super competitive and complement each other,” said manager Aaron Boone. “They all have different strengths, and they kind of protect each other in that way. They’ve been getting the job done for the most part all year.”

Also continuing to show encouraging signs was Anthony Volpe, who notched his fifth consecutive multihit performance in the win. Volpe roped a Matthew Liberatore pitch for a second-inning RBI triple, then added a single in the Yanks’ three-run ninth inning.

The rookie’s offensive performance has improved markedly since June 12, when he enjoyed a chicken parmesan meal at his parents’ Watchung, N.J., home with Minor League teammate Austin Wells, where they examined the rookie’s batting stance on an iPad.

In 16 games since that date, Volpe is batting .373 (19-for-51) with nine runs scored, five doubles, a triple, three RBIs and seven walks.

“He’s barreling up balls,” Boone said. “He’s doing a better job of not expanding as much. We’ve seen that now for two, three weeks, where it’s just been consistent at-bats. If you do that over time, the results will be there, and that’s really what we’ve seen from him.”