“Well, you still have those,” he added, laughing. “They’re called St. Louis Cardinals fans.”

In September 2013, one of Kurtz’s videos appeared, remarkably, on five ESPN programs. The star of that clip was Choi Jun-seok, a burly slugger and a sort of mythic figure among connoisseurs for the consistency and quality of his flips. Choi, then a member of the Doosan Bears, clouted a ball down the left-field line and chucked his bat violently toward third base, his arms raised in celebration.

The ball curled foul, and he had to walk over to retrieve his bat.

Choi, now a member of Lotte, said he never felt embarrassed about that play. It was an instinctive reaction, he said, so why would he?

“When I get the barrel on the ball, that pose just naturally comes out, and my hands move like that,” Choi said. “It’s not conscious.”

In describing swings that produce flips, Choi and many other Koreans invoked the term “shiwonhada” — a feeling without a convenient English translation. Koreans might use it to describe concepts like a cool breeze, a heartwarming stew, an open highway or a smooth golf swing. The bat flip, in this context, might be considered the rough equivalent of a satisfied sigh after a gulp of cold beer.

“I think if I was playing in America and did it, because it’s such a natural thing, people would understand,” Choi said.

Maybe. The bat flips of Zack Greinke, a pitcher for the Los Angeles Dodgers, have made him popular among many young fans, and this summer, the Major League Baseball social media team ran a bat-flip bracket on its Twitter feed that featured many of the league’s biggest stars. (How “bat-flippy” these were constitutes a separate debate: “They were bat drops,” Kurtz said.)