Carli Lloyd, the best women’s soccer player in the world for the past two years, recently scored her first goal for Manchester City’s women’s team in the Champions League quarterfinals. Lloyd made the move this February and will remain with the team until June, when she plans to return to the Houston Dash.

Lloyd’s move isn’t the only one of its kind. Lloyd’s fellow US women’s national team star Alex Morgan made the move in December to play for Olympique Lyonnais in France, a women’s team that has won 10 straight Division 1 Feminine titles and last year’s Champions League title.

While both players plan to return to NWSL, their decisions to forego the start of the season in the states shows a shift in the power structure of women’s soccer. The United States failed to win an Olympic gold medal for the first time since 2000 this past summer, falling in the quarterfinals after a shaky group stage performance. After winning two of the first three Women’s World Cups and dominating the women’s soccer scene during the 1990s, the team, while still a powerhouse, didn’t win another World Cup trophy until they rode a hot streak from Lloyd to a victory in 2015. In that time, Germany won back-to-back titles in 2003 and 2007, and Japan defeated the US on penalties in 2011.

The competition continues to stiffen for the USWNT. At this years SheBelieves Cup, the Americans scored one goal in a 1-0 win against Germany and then were shut out in their next two matches — a 1-0 loss to England and a 3-0 humiliation at the hands of eventual champions France — on the way to a last place finish. All this came after winning the tournament the year before with a perfect 3-0 record.

The power balance in women’s soccer continues to shift, and it’s clear that Lloyd and Morgan sense it. In a December piece in The Players’ Tribune, Morgan wrote, “I hope that this change will help push my game to another level. I hope that training with these incredible athletes each day, and learning a unique style of play, is exactly what I need, and that it will help me find that next gear,” and n a New York Times article in February, Lloyd said she was “eager for the chance to challenge herself professionally and to soak in some experiences that have been long beyond her reach.”

In addition, forward Crystal Dunn and midfielder Heather O’Reilly have made more permanent moves abroad to Chelsea and Arsenal, respectively. As the NWSL continues to grow, the US stars’ exodus in search of better competition, both in games and in training, threatens to stunt the young league’s progress in its fifth season.

With the USWNT faltering on the international stage, it may be just what the national team needs to regain its competitive edge. However, should the league falter, American youth development could lag behind, and the depth of the talent pool for Jill Ellis, or any future manager of the women’s team, could disappear.

It remains clear, however, that the domestic league needs to adjust to compensate for its fleeing international stars. Europe’s women’s soccer infrastructure is far more stable than the CONCACAF region’s, and the fact that the clubs, and leagues, are so established is what makes a move overseas more attractive. The French women’s league was founded in 1974, the Spanish league, in 1988, and the German league in 1990, just to name a few.

For comparison, Mexico’s women’s soccer league is in its debut season, and while Canada’s professional system is tied with the United States’, the country to the north has no teams in the ten team NWSL, compared to its three teams in the corresponding men’s league, MLS.

The NWSL is the United States’ third attempt at a professional women’s soccer league. Neither of its previous two lasted for more than five seasons. The moves overseas of the USWNT stars reflect a more stable professional environment in Europe. Meanwhile, the NWSL will no doubt struggle without the world’s biggest stars to market its product.

The returns of Lloyd and Morgan will boost the league’s popularity, but it needs to sustain itself beyond just its stars. Lloyd and Morgan won’t be around forever, and the USWNT no longer looks invincible on the world stage. The American interest in women’s soccer will wane when the US is no longer making runs to the final of every major tournament, and the constant victory tours that lead to 8-1 wins over Romania aren’t compelling: There’s simply no competition.

What determines whether the league sinks or swims is how it adjusts to its players leaving for a better situation across the Atlantic. Maybe it takes a David Beckham-esque signing to jumpstart the league’s growth (the only player I can really think of that can generate this is Marta. Five FIFA Women’s player of the year awards has to count for something), but unless it can find a way to attract more big names, it will inevitably fail.

More presently, however, the NWSL must find a way to sustain itself until the return of its stars in June. The league is dependent on the post-World Cup popularity, when the nation is wrapped up in the accomplishments of its biggest stars. Lloyd and Morgan have reliably carried the torch for the league. The responsibility now falls on the largest remaining stars in the league, midfielder Tobin Heath and forward Christen Press. If more stars move overseas, the NWSL is doomed to fall, like the two American women’s soccer leagues before it.