In early February, a couple of weeks after turning twenty-one, a minor-league baseball player named Kyle Tucker went to his local batting cage, in Tampa, Florida, and impersonated Ted Williams. He put on, as he recalls, “big, wool, baggy pants,” “old-time cleats,” and a Red Sox jersey from the nineteen-fifties, with the requisite No. 9. He chose from among several vintage bats acquired via eBay, selecting what he felt was “kind of just like a log—like a tree trunk.” His mom accompanied him. He brought a friend to pitch to him. The friend wore wool, too: Orioles garb. The baseballs were contemporary, but white nail polish obscured the M.L.B. logo and the commissioner’s signature. Rosin was added for visual effect. Tucker, who is tall and lean, like Williams, made a few minor adjustments to his usual lefty stance. “I had to lower my hands and elbow and try and get into a little bit of a crouch and lean over the plate a little bit more,” he said recently. A camera filmed him as he hit, capturing two thousand frames a second, against a black screen. Nick Davis, who was directing the shoot (and dressed as an umpire, for verisimilitude), estimates that, of the hundred cuts Tucker took, he “smacked the shit out of the ball” ninety-eight times.

Tucker is not named in the credits of “The Greatest Hitter Who Ever Lived,” a documentary about Williams that premieres on PBS, on Monday, as part of the “American Masters” series, nor does his face appear in any of the footage Davis ended up using, to emphasize his subject’s “mythical” appeal. Initially, Davis had thought of casting a known big leaguer as Williams’s stand-in. He thought of swings he admired for their elegance, like those of the Nationals’ Daniel Murphy and the Dodgers’ Corey Seager. But after some YouTube scouting, he concluded that neither of those players would suffice. They were too visibly muscular and, therefore, not as graceful. He sent an e-mail to a contact at Major League Baseball, asking for help. “Given the way weight training has affected players’ bodies, maybe we need to be looking at amateurs or even high schoolers who haven’t bulked up their bodies yet,” he wrote. “The good news is, we don’t necessarily need this guy to be a particularly great hitter—he just needs to look like one—the greatest hitter of all time.” The contact responded ten days later with a video of Tucker and a brief note: “Astros prospect. 6’4”, 190 lbs. Ted Williams is often mentioned in Kyle’s scouting reports and check out the slo-mo swing at 1:27.” There it was: the loaded hands, the exploding hips, the effortless uppercut. “It was incredible,” Davis said.

Davis worried about placing undue pressure on his actor—“if you look at the career of Darryl Strawberry, who came up as ‘the black Ted Williams,’ it was just too much,” he said—and struck a deal with the Astros to keep Tucker’s participation a secret. But when he reported to spring training, a few weeks after the taping, and was assigned to the major-league camp, his new teammates and coaches caught wind of the old scouting reports and insisted on calling him Ted, as a form of complimentary hazing. Soon he was hitting over .400. The “Tucker” nameplate above his locker disappeared and was replaced with a makeshift one: “TED.” His last at-bat of the spring resulted in a home run to right field, echoing the final at-bat of Williams’s career. On TV, the Astros’ play-by-play announcer exclaimed, “And the legend continues of Ted!” The embargo was lifted.

Tucker owns “The Science of Hitting,” Williams’s treatise, but he is not given to philosophizing about his craft in the same way. Speaking of Williams (whom he called “that guy,” without ever speaking the full name aloud), he said, “I’m sure he was just trying to hit the ball as hard as he could in the air and drive the ball out of the park. I mean, that’s what we all try and do.” He’d begun the season in Fresno, and professed not to notice when, two weeks ago, the Astros’ general manager, Jeff Luhnow, celebrated his promotion to Houston by tweeting, “Ted is here,” along with—oddly—a GIF showing the Death Star activating its planet-destroying energy beam. Tucker struck out in his first three at-bats in the show, and was one for his first ten. (He is now four for twenty-seven.) His new teammates razzed him. “The guys were like, ‘Right now, you’re Tuck. You need to step it up a little bit to get the Ted name back.’ ” As of last week, Tucker still hadn’t told any of them about his cameo. “It never came up,” he said. “I don’t know why it would.”