But as a union leader, it was Miller who took on baseball's establishment in the late 1960s, eventually guiding players to an era of mega-salaries and free agency, thereby changing the landscape of American sports.
PHOTOS: Notable deaths of 2012
Miller died Tuesday at his home in Manhattan, several months after being diagnosed with liver cancer, his family announced. He was 95.
Historian Studs Terkel characterized him as "the most effective union organizer since John L. Lewis," the legendary mine workers leader. Hank Aaron, one of the game's most-prolific home run hitters, wrote that he "should be in the Hall of Fame [even] if the players have to break down the doors to get him in."
During Miller's tenure as head of the Major League Baseball Players Assn. from 1966 to 1982, average salaries rose from $19,000 to $241,000, in large part because he fought baseball's antitrust exemption and gave players the right to move from team to team.
"Marvin possessed a combination of integrity, intelligence, eloquence, courage and grace that is simply unmatched in my experience," said Donald Fehr, who later headed the players union. "Without question, Marvin had more positive influence over Major League Baseball than any other person in the last half of the 20th century."
But not everyone appreciated Miller. As basketball and football subsequently adopted free agency, fans saw higher ticket prices, work stoppages and a new order in which favorite players often switched teams.
"You may not like what he did," said David Carter, executive director of USC's Sports Business Institute, "but you can't argue with how he did it."
Before Miller's arrival on the scene, owners dominated the sport. It came as a shock when Dodgers stars Sandy Koufax and Don Drysdale held out for more money in 1966, the team eventually signing them for $125,000 and $110,000, respectively.
That same spring, the ineffective players union went looking for a leader and was referred to Miller.
Born April 14, 1917, he had grown up in Brooklyn, and his fondest childhood memories included Dodgers games at Ebbets Field, a short subway ride from home.
Miller received an early education in trade unionism from his father, a garment district salesman who organized fellow workers. After graduating from New York University, he worked for the New York City welfare department before taking jobs as an economist with the War Production Board and the War Labor Board during World War II.
"It was kind of like a utopian dream," he said of the latter board, created to handle disputes between management and workers. "And it worked remarkably well."
Miller subsequently moved to the United Steelworkers, where he spent 16 years as a research economist and, later, assistant to the president. In 1963, President Kennedy appointed him to a national labor management panel.
After the players union approached him, Miller made the rounds at spring training, facing opposition from wary players.
"The club owners are saying that you're one bad guy; they're saying terrible things about you," he recalled hearing.
Miller told them: "If I represent you and, at some point down the road, you begin to hear management people praising me, it's time to fire me."