The United States Women's National Team celebrates after beating Japan in the FIFA Women's World Cup soccer championship in Canada in July 2015. (AP Photo/Elaine Thompson, File)

In the 2016 fiscal year, the U.S. women's national soccer team earned $23.5 million in revenues for games it played in America. That was triple the revenue the U.S. Soccer Federation predicted in its budget for the year, and it was more than the men's national soccer team earned from games in the same time period.

For the 2017 fiscal year, which begins Friday, the Federation projects the women's team will bring in about $17.5 million in game revenues, turning a $5 million profit in the process. It projects the men's team will earn about $9 million in game revenues and net a $1 million loss.

If you didn't know much about soccer, or gender dynamics, or really anything outside of standard green-eyeshade accounting and entry-level economics, you still might form an obvious conclusion from those numbers: that the players on the U.S. women's soccer team are highly productive investments. You'd want to give them more money, to encourage them to play more soccer, to generate more revenues and higher returns.

And if you want people to do more of something -- again, this is entry-level economics -- you typically pay them more.

That is not the conclusion of the U.S. Soccer Federation. According to a federal wage discrimination complaint filed Thursday by five stars of the women's 2015 World Cup championship team, women earn far less than men for representing America on the international pitch. The complaint says the Federation pays women nearly four times less than it pays male players, according to ESPN.

The New York Times reports that "a men’s player, for example, receives $5,000 for a loss in a friendly match but as much as $17,625 for a win against a top opponent. A women’s player receives $1,350 for a similar match, but only if the United States wins; women’s players receive no bonuses for losses or ties."

The complainants cast this as a matter of fairness, which, to be clear, it is. “The pay disparity between men and women is just too large," World Cup hero Carli Lloyd told NBC, "and we want to continue to fight."

This is about more than fairness, and more than soccer. Paying hyper-talented women less than their male counterparts, when they are performing better against their competition and - yes - raking in more dollars, sends a backwards market signal to current and future players. It blunts the incentive for very talented women to pursue soccer stardom, which potentially hurts the nation in international competitions - and the Federation in its bottom line.

The same can be true in the economy at large. If talented women are paid arbitrarily less than similarly talented or less-talented men, the market is telling those women to work less than they optimally would. We're talking true "equal pay for equal work" here; a compensation gap that does not reflect actual differences in productivity between workers. There is plenty of evidence that such a gap exists.

Some economists believe it is a factor in one of America's most economically baffling trends of the 21st Century: Fewer women are working, as a share of the workforce, than they used to, even though women are more likely than men to graduate college and gain the skills that are in the highest demand in our increasingly service-based economy. At the same time, American productivity growth has slowed. One way to speed it up would be encouraging more highly productive women to do the work they're best at.

“Sports are actually the perfect example of discrimination," says Heather Boushey, a liberal economist who runs the Washington Center for Equitable Growth think tank, and who deals with gender-gap issues in her upcoming book, Finding Time: The Economics of Work-Life Conflict. "You can see productivity clearly. It’s about winning the game. It’s about getting fans to show up.”

Boushey isn't a huge sports buff, but she talks a lot about "leveling the playing field" for workers, in order to avoid "leaving talent on the sidelines." Policies that achieve such a leveling, she says, "would go a long way toward boosting productivity and boosting the competitiveness of the US economy.”

It has been lost a bit in the populist furor of the 2016 presidential campaign, but this is a main argument of the candidate betting markets rate as the overwhelming favorite to win the White House. Hillary Clinton has, from the start of the race, preached the idea that paying women more, for equal work, would give the United States an economic boost.

She's phrased that argument in all sorts of ways, but none so on point to today's news as in this tweet, from October, when a Republican senator blocked consideration of a measure urging equal pay for the women's and men's national teams.

"Whether you're a teacher, an executive, or a world-champion soccer player," Clinton wrote, "you deserve equal pay."

Expect to hear a lot more of that in the months to come. The women's team will try this summer for another Olympic gold medal. The men's team, sadly, did not qualify.