“You know, in my next life, when I come back, I want to be someone in the WTA [Women’s Tennis Association] because they ride on the coattails of the men,” Moore said. “They don’t make any decisions, and they are lucky. They are very, very lucky. If I was a lady player, I’d go down every night on my knees and thank God that Roger Federer and Rafa Nadal were born because they have carried this sport. They really have.”

He subsequently resigned amid the backlash, but his views are shared by at least some top men’s players. Novak Djokovic, the world’s No. 1 men’s player, suggested that professional tennis should pay men more because they attract high viewership. That argument notwithstanding, pay equality in tennis, as my colleague Adam Chandler reported, “isn’t a cut-and-dry issue. In Grand Slam tournaments, men have to win three sets to advance while their female counterparts have to win two.”

But that’s clearly not the case with soccer. For starters, both men’s and women’s games are 90 minutes long. Then, by most measures, the women’s team is not only more accomplished, but also more popular. The women have won three World Cups and four Olympic gold medals. The men have not come anywhere near that. And last July, the Women’s World Cup final set a record for TV viewers––for women’s soccer, and men’s.

The players’ lawyer, Jeffrey Kessler, said the complaint with the EEOC, which handles workplace-discrimination issues, is as strong as he has seen, “because you have a situation where not only are their work requirements identical to the men’s requirements—the same number of minimum friendlies they have to play, the same requirements to prepare for their World Cups—but they have outperformed the men both economically and on the playing field in every possible way the last two years.

“So this isn’t a case where someone can come in and say the reason the men are paid more is because they are more economically successful or the men outperform the women or they’re not comparable in the same way,” he said.

And it’s not just pay from U.S. soccer that is unequal. For a long time, the women’s team has complained that everything from the referees who call their matches, to the fields they play on, don’t compare with the men’s. Last December, the women canceled a game against Trinidad and Tobago in Hawaii because the artificial turf, they said, was peeling and laden with rocks.

U.S. Soccer said in a statement, sent to ESPN, that it hadn’t seen the specifics of Thursday’s complaint, but that it’s disappointed.

“We have been a world leader in women’s soccer and are proud of the commitment we have made to building the women’s game in the United States over the past 30 years,” the statement said.