When the New York Yankees baseball team crossed a hotel workers’ picket line in Boston last week, Marvin Miller must have turned in his grave. Miller, the first executive director of the Major League Baseball Players Association (MLBPA), from 1966 to 1983, freed players from indentured servitude. Because of the players’ union, the Yankees and their counterparts on 29 other teams are among the highest-paid athletes in the world.

But soon after they arrived in Boston to play the Red Sox in the American League division series, the Yankee players crossed union picket lines at the Ritz-Carlton hotel, where employees were in the second day of their strike.

Videos revealed several players, including outfielder Brett Gardner (whose current salary is $12.5 million) and pitcher Dellin Betances ($3 million), carrying their suitcases into the hotel while striking workers chanted, “Don’t check in, check out.”

From a union perspective, the Yankees not only checked in, they also struck out. Someone should teach these muscular millionaires how to sing “Solidarity Forever.”

Brian Lang, president of Local 26 of UNITE HERE, the hotel workers’ union—whose 1,500 members went on strike at seven Marriott-owned hotels in Boston, including the Ritz-Carlton—recognized that while it was Yankee management, not the players, that booked the hotel, it was “a flimsy excuse for crossing a picket line.”

“As a lifelong Yankee fan and a proud New Yorker, I am disgusted the management of a team representing the strongest union town in America would choose a hotel where workers are on strike,” said Mario Cilento, president of the New York State AFL-CIO.

Ironically, the MLBPA is now the most successful union in the country. In 1967, the year after Miller took the helm of the union, the minimum salary was $6,000 ($45,984 in today’s dollars) and the average salary was $19,000 ($145,616). This year the minimum salary is $545,000 and the average salary is $4.5 million.

Most players make far above the minimum. Yankee pitchers CC Sabathia, Masahiro Tanaka, and Aroldis Chapman earned $25 million, $22 million and $17.2 million, respectively, this year. Pitcher Dave Robertson (the Yankees’ union player representative) made $12 million.

Marvin Miller was a hard-core union man—he came to the MLBPA after a long career with the United Steelworkers of America—who brought baseball players respect and money through his tough negotiations with team owners and emphasis on player solidarity. He constantly reminded players that the owners were united to keep their pay and perks as low as possible, so the players needed to be united, too. He also educated the players that they were part of the broader labor movement and to respect the struggles of other union members and people who weren’t as fortunate as themselves.

“People today don’t understand how beaten down the players were back then,” Miller told us in 2008, four years before he died. “The players had low self-esteem, as any people in their position would have—like baggage owned by the clubs.”

Before Miller took the reins, players were tethered to their teams through the “reserve clause.” Their contracts “reserved” the team’s right to “retain” the player for the next season. Each year, the team owners told players: Take it or leave it. Even superstars went hat-in-hand to owners at the end of the season, begging for a raise.

Miller instructed ballplayers in the ABCs of trade unionism: Fight for your rights to be treated as more than property, stick together against management, work on behalf of players who came before you and would come after you, and don’t allow owners to divide players by race, income, or their place in the celebrity pecking order. He taught the players about labor law and history, alerting them to their own power and training them to outmaneuver the owners during negotiations. Under his leadership, the players won a democratic voice in their workplaces and dramatically improved their pay, pensions, and working conditions.

Two years after Miller joined the MLBPA, the union negotiated its first collective-bargaining agreement, which established the rights to binding arbitration over salaries and grievances and to allow agents to negotiate their contracts. In 1976, the players won the right to become free agents. This gave players the right to decide for themselves which employer they wanted to work for, veto proposed trades, and bargain for the best contract. The union also won better travel conditions, training facilities, locker-room conditions, and medical treatment. In his 1991 autobiography, A Whole Different Ball Game, Miller called those changes “like the difference between dictatorship and democracy.”

Despite the MLBPA’s role in lifting today’s players into the economic stratosphere, the Yankees acted like the Ritz-Carlton’s striking housekeepers, cooks, doormen, and bartenders were invisible.

Ye Qing Wei, a 50-year old housekeeper, has worked at the Ritz Carlton for 13 years. Since the strike began on Wednesday, she’s been walking the picket line from 7 in the morning until 6 at night. Because the hotel doesn’t guarantee her steady work, “sometimes I lose hours and don’t have health insurance,” said Wei, who has two children in college.

Her mother—like her, an immigrant from China—is in her 70s and works at a Sheraton hotel in Boston. “She can’t retire,” her daughter explained, “because she doesn’t have any health insurance if she isn’t working.”

D. Taylor, the International President of UNITE HERE, pointed out that despite their millions, many of the players come from backgrounds similar to the striking workers.

“We wanted the Yankees to at least talk to our strikers and express their support,” Taylor said. “Whether they are from the Dominican Republic or the United States, these are people who could be the players’ mothers and fathers. It’s time for them to speak out.”

The Boston hotel workers—at least 60 percent of them women and 85 percent of them black, Latino, and Asian employees, including many immigrants—earn modest salaries. Housekeepers—by far the largest segment of the unionized hotel workforce—earn an average of $21.45 an hour, the equivalent of about $44,000 for those who work 40 hours a week year-round. But the union is calling on the hotel owners to provide steadier hours so that workers will have health insurance, a reasonable pay increase, and pension protections for workers approaching retirement.

According to Lang, president of the union’s Boston local, this is the first hotel strike in the city’s history. The workers’\ were pushed to the wall because for over a decade the area’s cost of living, particularly rents, has skyrocketed much faster than wage increases. The strike’s slogan, “One Job Should Be Enough,” reflects the harsh reality that many of the hotel workers take second and even third jobs to make ends meet. Meanwhile, Lang explained, the hotels have been making record profits for at least five years.

Ironically, the hotel workers’ slogan could have been used by professional baseball players before Miller arrived to run the MLPA. Most had to work second jobs in the off-season to make ends meet. During his 1999 Hall of Fame induction speech, Nolan Ryan reminded the audience that when he joined the major leagues in 1966, he spent the winter working at a gas station while his wife worked at a local bookstore. Because of the players’ union, Ryan said, “We brought that level up to where the players weren’t put in that situation.”

“We are fighting for exactly what the baseball players once fought for,” said UNITE HERE’s Taylor.

“I feel powerful because me and my co-workers are all together,” said Wei, the Ritz-Carlton housekeeper. “We don’t want to call them [the Yankee players] ‘scabs,’ but they should support us.”

The MLBPA issued a short statement regarding the Boston strike: “From what we understand, these workers have been trying to negotiate a fair contract for more than six months. They deserve to be heard and they deserve our support.”

The players’ union spokesman was talking the talk, but not a single Yankee player bothered to walk the walk—literally, to join the picket line or walk out of the hotel and demand that the team find another union hotel, where workers aren’t on strike, for the players, coaches, and other personnel to stay in.

Although baseball players are generally less outspoken and progressive than their NFL and NBA counterparts, over the years a handful of major league players—including Sam Nahem, Danny Gardella, Jackie Robinson, Roberto Clemente, Jim Bouton, Curt Flood, Bill Lee, and Carlos Delgado—have expressed their liberal and even leftist political views.

Donald Trump’s election triggered an upsurge of tweets and comments by players opposed to his immigration policies and white supremacist comments. During the 2016 presidential election, for example, Los Angeles Dodgers first baseman Adrian Gonzalez refused to stay at a Trump hotel. Asked to explain his action, Gonzalez simply told reporters, “You can draw your own conclusions. They’re probably right.”

On the night of Trump’s election, his Dodger teammate Brandon McCarthy tweeted: “Tonight’s result affects me none because I’m rich, white and male. Yet, it’ll be a long time until I’m able to sleep peacefully.” Houston Astros pitcher Collin McHugh, an Atlanta resident, also slammed the president after he attacked civil-rights pioneer and Georgia Congressman John Lewis.

CC Sabathia and his Yankee teammates visited Barack Obama in the White House after they won the 2009 World Series, but a year ago the pitching ace told the New York Daily News that he would “never” visit the White House with Trump in office. “I just don’t believe in anything that is Trump. So there wouldn’t be any reason for me to go at all.”

Despite his outspoken criticism of the president, Sabathia joined his teammates in crossing the union picket line in Boston. But deciding on hotel accommodations is the responsibility of teams’ management, not the players or their union. And the Yankee players were understandably focused on beating the rival Red Sox for the division championship.

The Red Sox beat the Yankees on Tuesday to advance to the American League Championship Series, where they will meet the Houston Astros. If the Boston hotel workers are still on strike against the Marriott chain when the Astros play in Fenway Park—and if the Red Sox make it into the World Series—the MLBPA should insist that opposing teams visiting Boston stay in a union hotel where workers are not on strike.

It would also a nice gesture for a few Red Sox players—as well as players from the opposing teams and even teams that didn’t make it into the post-season—to show up and join the hotel workers’ picket line. That photo op would go a long way to putting the players back in the good graces of baseball fans who, like most Americans, have seen their wages and family incomes stagnate or even decline over the past decade.

One way to avoid putting major-league players in an embarrassing situation would be to insert language in their union contract that requires teams to stay in union hotels and to prohibit teams from staying in hotels where workers are in the middle of labor disputes with management, so players don’t have to cross picket lines. (Only three of the 26 cities with major league teams—Cincinnati, Tampa, and Arlington, Texas—don’t have union hotels.)

The MLBPA should go back to being a union in the Marvin Miller tradition. When the players have gone on strike or been locked out by owners—which has happened eight times since 1972—other unions have supported their actions. The Teamsters, for example, honored the players’ picket lines and refused to deliver food and other supplies to stadiums during the MLBPA’s 232-day strike in 1994.

The MLBPA should also follow the example of the NFL Players Association and join the AFL-CIO, the organization that promotes solidarity among all unions.

If ballplayers show their support for struggling workers—starting with the hotel workers in Boston—they can count on public support the next time baseball’s team owners decide to come after them. Otherwise, even baseball fans will continue to view the players as overpaid and out of touch.