The recently concluded European transfer window has the potential to be a watershed moment for U.S. players. It wasn't so much how many players moved, but where they went. Weston McKennie left Schalke 04 to join Italian giants Juventus, and Sergino Dest completed a transfer from Ajax to Barcelona, amid significant interest from Bayern Munich and Paris Saint-Germain.

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The moves marked the first time that American players had been transferred to such historic clubs, but to be fair, Americans have been burrowing their way into bigger European teams for a couple of years.

There was Christian Pulisic's transfer from Borussia Dortmund to Chelsea in 2019, and Tyler Adams moving from the New York Red Bulls to RB Leipzig the same year. Last season Giovanni Reyna rose through the ranks at Dortmund, and now Chris Richards is doing the same at Bayern Munich. Konrad de la Fuente is on the verge of receiving his first competitive minutes with Barcelona's first team. There's even a U.S. manager involved in this year's Champions League group stage in FC Salzburg's Jesse Marsch.

To get an idea of just how big a shift has taken place, five years ago, Fabian Johnson of Borussia Monchengladbach was the only American player in the group stages of the UEFA Champions League. This time around, while not every American is in a starting role, 10 such players have made their way onto Champions League rosters. Eight of the 10 are under the age of 23.

The U.S. men's national team is poised to be the biggest beneficiary. The kind of experience being gained by U.S. players should give manager Gregg Berhalter and his team a deeper well of talent to choose from, and prepare them for World Cup qualifying.

"I will go as far as to say that a mark of any country's potential success is directly related to the amount of players they have competing in the Champions League," Berhalter said. "In those games you either sink or you swim. The game is the great revealer. When you have a guy who can go in there, on that stage, and play and hang in there, they ought to be able to do the same thing in the World Cup, because they are similar types of games."

But even as American players make deeper inroads at the game's elite clubs, the reality is that what has taken place isn't the end, but another step. And it's not enough to simply be on the roster of a great club.

"I think it's great. I understand when that opportunity comes that you have to take it," said former U.S. international and current ESPN analyst Kasey Keller, about the recent transfers. "I understand that then you have to challenge yourself. But it is about minutes and playing time. In the end, it really has to be about: Are these guys playing week in and week out? Are they integral parts of their clubs going forward?"

The other question the development raises is whether this is a signal that the U.S. is doing a better job of developing players, and here, the individual circumstances do vary. Dest (Netherlands) and Konrad (Spain) were developed entirely outside the U.S. system. Others, like Pulisic and Reyna, benefited from obtaining European passports that allowed them to head to Europe at age 16 instead of 18, an age range at which the U.S. system has historically struggled to move players along.

But there are success stories like Adams and Richards, and in recent weeks, more than 40 players eligible for youth national teams have been getting playing time in MLS. All of which hints that in terms of development, incremental steps are the norm as opposed to quantum leaps.

"I think we're gaining momentum in international soccer with some of these moves, and I've said it all along is, this isn't a result of this transfer window," Berhalter said. "This is a result of years and years of work in the developmental space, both by U.S. Soccer with the Development Academy, and then MLS owners, and for them to put all the resources into the infrastructure and the pathway and the coaches." -- Jeff Carlisle

USMNT Stock Watch: Who's up? Who's down?

How are the players Berhalter will be relying upon for World Cup qualifying performing with their clubs? ESPN's correspondents from around the world bring you inside information to help explain the successes and stumbles of American players around the world.

Giovanni Reyna -- On the rise : Reyna has featured in all five of Dortmund's competitive fixtures so far this season, registering a pair of goals and three assists. The 17-year-old has bonded with fellow prodigies Erling Haaland, Jadon Sancho, Jude Bellingham and Reinier, helping the latter settle into life in Germany following his loan move from Real Madrid. Sources tell ESPN's Stephan Uersfeld that Dortmund see similarities between Reyna and Marco Reus, specifically noting the teenager's defensive improvement and aggressiveness on the ball -- just like his captain.

DeAndre Yedlin -- Trending down : In Newcastle's first seven matches of the 2020-21 season, Yedlin has made just three matchday squads -- two starts in the Carabao Cup, and as an unused sub in the Premier League draw vs. Tottenham. The 27-year-old is now the third-choice right back on Tyneside, with sources telling ESPN that there are doubts about his defensive positioning. The former Seattle Sounders standout had been linked with a move away all summer, but wages proved to be an issue, sources say. If he isn't named to Newcastle's Premier League squad next week, he could be motivated to find a new home in January.

Tim Ream -- Holding steady : It's been a rough start to Fulham's return to the Premier League, with no points and 11 goals conceded in four matches. Ream has started three of those games, and another in the Carabao Cup, demonstrating his value to manager to Scott Parker. However, the Cottagers brought in two center backs on deadline day, putting the 33-year-old's place under threat. Sources tell ESPN's Jeff Carlisle and Tom Hamilton that there's "no panic" from Ream's camp, and that he's prepared to compete for his place, citing the nearly 20 center backs who've moved to Craven Cottage during his time at the club and failed to displace the former Bolton man.

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Timothy Weah -- Trending down : Weah has featured in just 31 minutes of Lille's six Ligue 1 contests this year. Sources tell ESPN's Julien Laurens that the French side is being cautious with the 20-year-old after a pair of hamstring injuries cost him nearly all of the 2019-20 season, his first after leaving Paris Saint-Germain. But that's not the reason for his lack of action this term, with manager Christophe Galtier wanting Weah to play as a center forward, where Burak Yilmaz and Jonathan David are the preferred pairing atop Lille's 4-4-2. Weah is said to be frustrated by his lack of action as the third-choice striker, but remains in good spirits and awaits his chance with Yilmaz and David netting just two league goals between them.

A few minutes with ...

For most of the summer, Weston McKennie had been linked with a move to the Premier League, so it came as some shock when he joined Italian giants Juventus on loan in August. Since, the 22-year-old has started all three matches in the Bianconeri's young campaign, including the first two games of their Serie A title defense.

The FC Dallas academy product sat down with our Matteo Bonetti to talk about his decision to move to Turin, how he's settling into life in Italy and what it's been like to join a dressing room full of stars he has grown familiar with through years of playing FIFA.

Scouting report

Another tremendously gifted teenager from the impressive pack of American talents in European football, California-born Ulysses Llanez has Mexican parents and was close to representing Mexico at youth levels before settling for the U.S. youth national teams. After impressing at various youth levels, he made his USMNT debut in a friendly against Costa Rica in February, playing the full 90 minutes.

A skillful, unpredictable winger with a frightening turn of pace, the 19-year-old has evidently been inspired by the likes of Lionel Messi and Neymar, as demonstrated by his trickery, quick feet and ability to deceive an opponent. But he's not merely dribbling for the pure fun of it; he's very positive in his play, tending to look for the direct route to goal when taking on opponents -- although, like most teenagers, he can be found running into blind alleys. Llanez also possesses a fearful strike on the ball with his preferred right foot (although he's practically two-footed) and he's always looking to pick the early pass in behind when drifting into playmaking positions in the middle of the field.

The loan move to Heerenveen should offer the American a gentle yet educational environment in which to undertake his baby steps in European senior football (Real Madrid prodigy Martin Ødegaard spent a rewarding 18 months at the same club beginning in 2017). In the Eredivisie, where he made his debut as a second-half substitute earlier this month, he will be looking to develop the defensive side of his game and get on the ball more frequently. -- Tor-Kristian Karlsen