With his bat, his glove and his flair, Dave Parker put himself in the pantheon of All-Star Game performers. He won the first Home Run Derby, in 1985 in Minnesota, six years after his throwing arm earned him the All-Star most valuable player award in Seattle. That was in 1979, when his Pittsburgh Pirates won the World Series.

“We took on the role of being the Black people’s team,” Parker, 70, said by phone this week. “We had 12 different combinations of uniforms, we had flamboyant players. If we hit a ball and it got past the first baseman, you’d better be on defense because somebody’s going to be taking second base.”

The 1979 Pirates had 10 Black players on their World Series roster, even more than the National League All-Star team included that season. That was near the height of African American participation in the majors, which peaked at 19 percent in 1986. On opening day 2021, according to Major League Baseball, that figure had dipped to 7.6 percent.

“It saddens me,” said Parker, who highlights the bygone era in his memoir, “Cobra: A Life of Baseball and Brotherhood,” released this year by the University of Nebraska Press.

“They’re missing speed. They’ve got that 24th or 25th man who’s not a brother, who used to be a brother. You’ve got Black players that can do multiple things, not just pinch-hit, but go out and steal a base, make an outstanding play. I just think they’re ignoring the Black player.”

The absence of the Black American player will be stark at Tuesday’s All-Star Game in Denver. Of the 32 All-Stars named to the original N.L. roster — before the Mets’ Taijuan Walker was picked as a replacement late Friday night — only one was Black: Mookie Betts of the Los Angeles Dodgers. Betts was also the only Black player among the 55 who participated in World Series last fall between the Dodgers and the Tampa Bay Rays.

“That’s unbelievable,” said Al Oliver, 74, a seven-time All-Star in the 1970s and ’80s. “I didn’t realize that. There’s one.”

Oliver, who played most of his career with the Pirates, was born six months before Jackie Robinson broke baseball’s color barrier in 1947. Growing up in Ohio, Oliver said, he gravitated to baseball because “you saw someone who looked like you.” At his first All-Star Game, in 1972, Oliver had 11 Black teammates on the N.L. roster, including Nate Colbert, Lee May, the Hall of Famers Fergie Jenkins and Billy Williams and several others bound for Cooperstown.

“McCovey, Morgan, Stargell, Brock, Mays, Aaron, Gibson,” Oliver said. “It was almost an all-Hall of Fame team.”

The disappearance of so many Black players from the modern game is one of the most critical problems for a sport seeking ways to stimulate action on the field and raise its appeal through crossover stars.

The game is loaded with dynamic talent, including those pictured on the banner of M.L.B.’s Twitter account: Ronald Acuna Jr., Shohei Ohtani, Fernando Tatis Jr., Jacob deGrom and Vladimir Guerrero Jr. All are magnetic attractions, though none are African American — and when a sport loses some 60 percent of any demographic in 35 years, something vital must be missing.

“Diversity in our game is important — it has been and will continue to be — and athleticism in our sport is important,” said Tony Reagins, the chief baseball development officer for M.L.B. “I think those two things go hand-in-hand — also the coolness, youthful, societal impact that the game, in terms of diversity, can have on culture itself. All those things lend themselves to the importance of African Americans, specifically, being a part of the game in a significant way.”

Reagins, who is Black, is the former general manager of the Los Angeles Angels. He joined M.L.B. in 2015, tasked with overseeing the development of youth baseball and softball, with an emphasis on encouraging Black participation. Reagins had hoped to see more progress at the major league level by now.

“When I first arrived on the scene in New York and we were building this department, I thought five years was a legitimate target,” Reagins said. “And once you start pulling back the layers of the onion, there’s a lot of work to be done.”

The pipeline is promising enough: From 2012 through 2020, 17.6 percent of first-round draft choices (51 of 289) were identified as Black or African American. The league has several on-field diversity initiatives, including a summer invitational, urban youth academies, a partnership with the Jackie Robinson Foundation and a $10 million donation — made with the players’ union — to the Players’ Alliance, a group focused on improving the representation of Black Americans on the field and in the front office.

In time, it seems logical that those efforts will produce more major leaguers. But Reagins outlined some core causes of the decline that are largely out of baseball’s control.

“Economics is a big part of it, too, in terms of the cost that it takes to participate in some of the travel or showcase tournaments, and some of the higher-priced equipment that’s out there,” Reagins said.

“I think the decline of the Black church is a part of it. And one of the other issues that is real is the lack of college scholarships available compared to the other sports, football and basketball.”

Essentially, baseball presents three significant financial barriers: the cost of equipment (bat, glove, helmet, spikes); the cost of the now-essential youth travel and showcase circuit; and the cost of college, with Division I baseball programs allowed only 11.7 scholarships, most of them partial. Men’s basketball teams get 13, and football teams get 85.

“I think a lot of kids would like baseball, but they don’t even get an opportunity to try it out at a young age because of how expensive it is,” said Ke’Bryan Hayes, the Pirates’ rookie third baseman and the son of the longtime major leaguer Charlie Hayes.

“It all boils down to getting the game out there to those kids at a very young age,” Hayes, 24, continued. “By the time you get to middle school or high school, it’s too late to try to learn baseball, because it’s one of the hardest sports. Growing up, I played with a bunch of kids that were really, really good, but they couldn’t afford to be able to go to that D-1 college. At some of these schools, even if you get a 40 or 50 percent scholarship, your parents are still going to have to try to pay $20,000 or $30,000 a year to go.”

As his career goes on, Hayes said, he hopes to help create opportunities for underprivileged children to play the game. He said he was encouraged by some of baseball’s efforts, citing the Players’ Alliance and the Breakthrough Series, a prospect camp for players of color funded by M.L.B. and U.S.A. Baseball.

But for now, there is no telling how much the sport has lost, in on-field excitement and off-field appeal, by losing so much Black talent.

“It made it more competitive,” Parker said. “Playing against other Black players, we didn’t give ’em no slack. We went out, we didn’t compromise. I’d take Ozzie Smith out to left field with a slide, if I could get him. We just enjoyed competing and loved each other.”