After 3 1/2 seasons, Freddy Adu, who was with Major League Soccer’s Real Salt Lake team, has departed to Portugal, where he has joined the Lisbon club Benfica.

Right from the start, when Adu joined MLS as a 14-year-old player back in 2004, there never seemed to be any doubt that his extravagant talent would eventually entice one of Europe’s top clubs to swoop and pay lots of money for his contract.

This isn’t quite what happened: Benfica is a big club, but not one of the richest. They have paid MLS (which owned Adu’s contract) just $2 million. Compared with the $43 million that Liverpool just paid Atletico Madrid for striker Fernando Torres, and Manchester United’s $36 million payment to Bayern Munich for midfielder Owen Hargreaves, $2 million is a paltry sum.

Adu, it needs saying, has not lived up to his billing. The move to Europe is now a make-or-break deal for him. He has a couple of points to prove: He was never really given a chance in MLS because his playing time was too limited. He was also too often used as a flank player, rather than as an attacking midfielder, which he considers his true position.

There is substance in both those claims. But to my eye, woeful inconsistency has been Adu’s biggest problem. For over three years we’ve been seeing flashes of brilliance pretty regularly, but they’ve proved to be a series of false dawns peaking through far too many bleak games in which he was barely visible. It has not been an easy ride, but Adu has retained his enthusiasm and his confidence. Last month he played impressively as captain of the U.S. team in the under-20 World Cup. Benfica moved in soon afterward.

But even those stand-out performances have a negative side, as that was a youth tournament, and one of the main criticisms of Adu is that he is not built strongly enough to withstand the more bruising nature of senior soccer. Trying to fathom Freddy’s future has been a four-year occupation for American journalists, and even now there are no obvious answers. Certainly, he has the look of a youngster who has been pressured into a false stardom built more on hype than on performance. Where lies the fault for that? With MLS? Not according to the deputy commissioner of MLS, Ivan Gazidis, who said last week, “We’ve struggled with the expectations, not that we’ve placed on him, but that the media has placed on him.”

But it was not the press that called a conference at Madison Square Garden to trumpet Adu’s signing, and it was Nike, not the press, that offered the 14-year-old boy a $1 million contract. If Adu has disappointed so far, there is plenty of blame to be shared.

The hope now is that Adu will find his true soccer feet in Europe, playing for a not-quite top club in a country that has always shown an appreciation for the artistry of soccer — something that could never be claimed for MLS, with its insistence on putting forward a macho physical image.

For MLS, the bittersweet Adu experience is now over. But it leaves behind — unresolved and probably not resolvable — a much wider problem: MLS, like it or not, is now very much a part of the rapidly growing international trade in soccer starlets. As soon as it produces a promising young player, it will almost certainly lose him to a European club.

This has been the reality in countries such as Brazil and Argentina for decades, but MLS has to face up to the fact that its best young players now come already fired with the dream of playing in Europe — the true ambition of all top players — where they can earn much more money.

What kept Adu in America for so long? Yes, there was an understandable desire that a 14-year-old needed to be at home with his family.

But the main reason Adu stayed was a FIFA regulation that bans the international transfer of players under the age of 18. The regulation, which was introduced in 2002, has always looked questionable. It denies parents the right to decide what is best for their son. We are now learning that the rule is being widely ignored.

The discovery of starlets is moving with the times. Now we have a YouTube generation of players: Children and teenagers from almost everywhere in the world are seeking fame through widely viewed Internet clips in which they are featured doing all sorts of fabulous things with a soccer ball. Last week, Manchester United announced that it had “signed” Rhain Davis, a 9-year-old from Australia — his video is up on the Internet for all to see. Davis was born in England, and now his family will move back there. This is something that the FIFA regulation says is not permitted — any move must be “for reasons not linked to soccer.”

Maybe Davis is an exception, as he has British citizenship. But no such reasoning applies to Carlos Vela, a striker who was a key member of the Mexican team that won the under-17 World Cup in 2005. Almost immediately Vela — still under 18 — was rumored to have been sold by his club, Chivas of Guadalajara, to the English club Arsenal, a rumor that Arsenal managed to avoid either confirming or denying. Vela did go to Europe — to play for the Spanish club Celta Vigo, supposedly on loan from Arsenal. Vela is now over 18 and has acquired a European passport. The new rumors are that he will now join (or is it rejoin?) Arsenal.

At no point during the protracted Vela saga did FIFA speak up. Indeed, I am not aware that FIFA has ever acted to block an under-18 international transfer. The regulation — already deeply flawed, as it cannot be applied within the European Union, where it contravenes EU laws — would appear to be doomed.

Which means that MLS, until it can start paying competitive salaries, will be producing young stars to play in Europe. Actually, it may not even have that chance. Overshadowed by the Adu trade was the fact that another member of the American under-20 team will be moving to Europe. Defender Eric Lichaj has simply bypassed MLS to sign for England’s Aston Villa.

As YouTube videos proliferate, showing off their precocious teenagers, European clubs will latch on to ever-younger players. Davis was not the only video star last week. An even more stunning YouTube clip showed some wonderful skills from Pier Larrauri, a 13-year-old Peruvian, who has been snapped up by Bayern Munich. He will spend a year with the club in Germany. The German newspaper Süddeutsche Zeitung emphasized that Larrauri doesn’t have a contract. That would be against FIFA regulations.

Right.