Postseason baseball, this is Fernando Tatis Jr.

You’re looking at the wrong thing.

It’s understandable. A bat goes flying in the air, end over end, propelled into the night in a fit of passion, and it inevitably draws every eye laid upon it. There is something magnetic about a bat flip, and the one Fernando Tatis Jr. unleashed Thursday night — the night he introduced himself to baseball’s postseason with his trademark vigor — was oozing with polarity.

After watching it once or twice or 500 times — any number is acceptable, honestly — make sure to check the side view. And at the first half-flip or so of the 3½ revolutions of the bat’s ultimate journey, pause it, slow it down, scrub it at quarter speed.

Look at Fernando Tatis Jr.’s eyes.

For someone so jovial, so full of joie de vivre that it’s practically infectious, there is another side of Tatis. It rarely reveals itself. It’s not that he hides from it or subverts it. No. On the contrary, actually. He saves it for when he needs it.

And as Tatis’ San Diego Padres teetered on the verge of postseason elimination Thursday, out came the serious side of him — the brooding one, beaming intensity, flirting with anger. This bat flip wasn’t an expression of joy as much as a flying billboard to his teammates at whom he cast his glance. This, he was saying, is what we must be.

The Padres’ 11-9 victory over the St. Louis Cardinals in Game 2 of their wild-card series illustrated not just what they needed to be but what they’re capable of being as they prepare for a win-or-go-home Game 3 on Friday at 7 p.m. ET. Down their two best starting pitchers because of injuries, working bullpen games because of their replacements’ ineffectiveness, the Padres — the darlings of baseball, in no small part because of Tatis, their 21-year-old shortstop — trailed by four runs in the sixth inning when Tatis swaggered to the plate.

For more than three weeks, he had found himself in a desperate slump. Over the last 20 days of the season, Tatis hit .164/.242/.291, lost 125 points off his OPS and gave away the NL MVP award. He was frustrated, searching — and leaving 10 men on base over the first game-and-a-half of his first postseason wasn’t helping matters.

Then Giovanny Gallegos threw five consecutive sliders to Tatis, and he did not miss the fifth. It soared over the left-field wall, cutting a 6-2 deficit to 6-5. A batter later, Manny Machado took Gallegos deep to tie the game. An inning later, Wil Myers homered to put the Padres ahead by a run. Up came Tatis again, this time facing Daniel Ponce de Leon. Like Gallegos, he was in love with one pitch. Tatis saw fastball after fastball: two inside, one low and away, two over the plate to take the count full. The sixth was the best pitch of all: 97 mph on the outside corner — murder on most hitters.

Tatis blasted it to the opposite field. And together came the characteristic Voltron his teammate Trevor Rosenthal described after the game: talent, passion, competitiveness, intensity. It’s those latter two that Tatis rarely shows, or at least that get overwhelmed by his omnipresent smile and easy laugh. That’s what made his stare so profound. There was no mistaking it, and there is no mistaking him. Tatis represents so many of the great things about modern baseball, including a deep desire to win.

“We’re in the playoffs,” he said. “The game was not done. The job was not done.”

As he stared — as the bat twirled in the air — San Diego’s dugout convulsed with excitement. The first home run awoke the Padres. Machado’s invigorated them. Myers’ felt inevitable. Tatis’ second served as a reminder. Myers’ second made history.

Only once before had teammates homered twice in the same postseason game. It happened in Game 3 of the 1932 World Series. The teammates were Babe Ruth and Lou Gehrig.

“To be in the record books with those guys,” Tatis said, “you’re doing something right.”

Yeah. That’s a fair assessment. This better resembled the Padres who looked like the second-best team in baseball behind their division rivals and the team they’ll face if they beat St. Louis on Friday, the Los Angeles Dodgers. This was the Padres team that earned the nickname Slam Diego for its propensity to hit bases-clearing home runs. This is where Tatis plays nucleus and everything around him quivers with energy.

Only once before, Tatis said, has he unburdened his hands of a bat with such great propulsion. It came during the Dominican Winter League, when he was playing for Estrellas de Oriente, his hometown team — and one managed by his father, the longtime big league third baseman Fernando Tatis. Estrellas were perpetual losers. The Tatis family showed up and they started winning. In a late-season game, dad asked son to bunt. He botched two attempts. On the third pitch, he pummeled a ball over the left-field fence. Almost immediately, Tatis flung the bat in the air granny-style — two-handed with an upward motion that sent it so high it may not have landed yet.

That one didn’t come with the stare. It’s why for whatever Thursday’s may lack in elevation, it makes up for in emotion. It drew immediate comparisons to Jose Bautista’s infamous division series flip, and actually, that deserves more credence than the gut reaction that places Bautista’s atop an unscalable mountain. Because as much as Bautista’s flip is about the flip, yes, what really makes it — what separates it — is his face. Bautista’s stare could melt tungsten. It’s fleeting, though. A flash and then gone.

Tatis’ lingered. He glared into the dugout. He saw his teammates. He wanted to ensure they all saw him. Gravity pulled the bat back to earth. His look was bound by no such laws. It imprinted itself on everyone wearing a Padres uniform. His vibe, his soigne, everything that the world sees and gloms onto and uses as reasons that Tatis is so lovable — that’s fine, that’s what he wants, that’s what baseball needs. But this moment, this mien. It is impossible to forget.

That, they now know, is who Fernando Tatis Jr. is. They knew it before, too, but a baseball player’s full breadth is never clear until he reaches the postseason, sees the World Series trophy within sight and casts his lot. This cast went to left field, went to right field, went into the dugout of a team ready to ride its star, and it goes to Game 3, winner take all, with every eye certain to be trained on a 21-year-old who really is that flipping good.