The U.S. women's national team used to have the best goalkeeper in the world.

At the last World Cup, which the Americans won, it was Hope Solo. Before Solo took over and set a world shutout record, it was Briana Scurry, the goalkeeper who held the previous shutout record and helped the U.S. win in 1999.

But now, for the first time in nearly three decades, since the first-ever Women's World Cup in 1991, the USWNT is going to have someone other than Scurry or Solo in goal for a World Cup. It'll be Alyssa Naeher, who has some very big shoes – or, rather, gloves – to fill.

Naeher is not as good as Solo was in her prime. That's no knock on Naeher; after all, Solo was a generational talent in goal. But the question for the USWNT heading into this summer's World Cup is: Just how much of a drop-off there will be in goal compared to four years ago?

Looking at each goalkeeper's record can only provide so many answers. For instance, Naeher has conceded multiple goals in about 13 percent of her full games (six of 45) compared to Solo, who allowed multiple goals in 9 percent of her games (19 out of 202). Solo's goals-against average for the USWNT was 0.41 while Naeher's has been 0.64. But that ignores how good the defenses in front of each goalkeeper have been.

Alyssa Naeher has some big gloves to fill this summer at the World Cup. (Getty) More

Luckily, Opta Sports has been tracking the USWNT since 2015, and their data provides a more careful look at how Naeher and Solo really compare on the international level. Opta's data provides a useful sample size too – it measures 38 Solo starts compared to 41 Naeher starts.

Interestingly, Naeher has faced slightly more shots than Solo did last cycle, which hints that the USWNT's defense has gotten worse at preventing quality scoring chances from opponents. Solo faced an average of 5.9 shots per game, 1.9 of them on target, while Naeher has faced 6.4 shots per game, 2.2 on target. Naeher has had to make three or more saves in 11 games, while Solo only had to do so in six games.

But when it comes to making saves, Solo was clearly the better shot-stopper. Solo's save percentage was 79 compared to Naeher's 71 percent.

Where Naeher looks like an upgrade is in playing with the ball at her feet or passing with her hands.

Naeher's passing accuracy is 69 percent while Solo's was 65 percent. Naeher averages 27.3 touches per game and Solo averaged 22.6. Part of that may be that the USWNT has emphasized building out the back and using the goalkeeper in possession more, but part of it may be that Naeher is well-drilled on distribution in a way Solo wasn't.

"Alyssa's distribution with her hands is phenomenal," coach Jill Ellis said last year. "Her feet have gotten much, much better. Her choices, her selection, her confidence on the ball, all those things have improved. She's competitive in the air. Ultimately, what it comes down to with a goalkeeper is that decision-making piece."

Toward the end of that quote, Ellis hinted at the things that stats can't measure – intangibles like experience, leadership and mentality. Those are the qualities that determine whether a goalkeeper can change a World Cup. But with Naeher it's still an unknown.

With Solo, there was no doubt in her prime that she could be counted to make the big saves when needed. Against Australia in the opening match of the 2015 World Cup, for instance, Solo was called upon to make several big-time saves.

As Alex Morgan put it after that tournament opener: "Hope’s saves were huge, especially the volley from the cross. I don’t know if any other goalkeeper in the world would save that one. That was pretty amazing to see her save our butts."

But how Naeher will respond to the pressure of playing in a World Cup is yet unknown. That's why Scurry hasn't been shy an expressing concern about the USWNT's goalkeeping headed into France.

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