Will Piazon stand out at Stamford Bridge?
Have Chelsea done a good deal acquiring Sao Paulo striker Lucas Piazon, who joins the club next year when he turns 18?
Sao Paulo are certainly happy. The deal enables them to sell a player who has yet to appear in their first team, bring top-class centre forward Luis Fabiano back to the club - he scored 118 goals in 160 appearances for Sao Paulo between 2001 and 2004 - and still have some money left over.
Whether Chelsea can feel as pleased with themselves, only time will tell.
Piazon showed touches of class as Brazil won the South American Under-17 Championship but his performances can hardly be considered conclusive evidence either way.
Usually operating off the centre forward, he is tall, strong and elegant, two-footed and good in the air. But he also came across as a frustrated figure, fretting when things were not going his way.
Piazon celebrates victory in the South American Under-17 Championship. Photo: AP
Two years ago, Piazon was outstanding at the South American Under-15 Championship, finishing as top scorer with nine goals. This time around, he only managed three, none of them in the decisive second round.
Could this be a youngster who had an early advantage because he matured physically so quickly but, as time went on, stood out less as others caught up?
If conclusions drawn from performances at Under-17 level are unreliable, it is a different matter when it comes to the Under-20s.
Players in the South American Under-20 Championship are often already seasoned professionals. If not, it is still possible to judge whether they are ready for the big time.
Javier Mascherano is an obvious example. When he played for Argentina at the Under-20 Championship in 2003, he had yet to feature in the River Plate first team. Nevertheless, it was clear he was ready.
Just a few months later, he made his senior debut for his country, still without having played for River Plate. Within a year, it was impossible to imagine an Argentina side without him in it.
As I have made clear already, conclusions reached at Under-17 level are treacherous. After the South American Championship six years ago, I wrote a column that focused on the two stand-out players, Kerlon of Brazil and Elias Figueroa of Uruguay. Now 23, the world is still waiting for them to make an impact.
Kerlon was known for the extraordinary seal dribble, running with the ball bouncing on his forehead. In truth, there was much more to his game than that. He looked like an extraordinary talent but he has suffered one injury after another and his senior career has still to take off.
Figueroa is an elegant, left-footed striker. Superb for Uruguay's Under-17 side, he was much less impressive at Under-20 level. In senior football, he is frequently on the bench for minor Montevideo club Liverpool.
I also covered the World Under-17 Cup in Peru six years ago. The two big talents were Anderson of Brazil and Mexico's Giovani Dos Santos. More than half a decade later, Dos Santos has still not made the move from promise to reality and is currently on loan at Racing Santander from Tottenham, while Manchester United's Anderson is a very different player from the one who looked so exciting back in 2005.
There is so much ground to travel before players reach the senior ranks. Youngsters can change so much in just a few years - in technical, physical and psychological terms.
The physical effects can be obvious. Kerlon, for example, has had his career ravaged by injuries, while a serious one may well have robbed Anderson of his burst of acceleration.
There is also the phenomenon of premature physical development, as I have highlighted already. How does the youngster cope when the others catch up and he finds out that he is not quite as good as he thought he was?
Then there are the psychological changes. This is an age when everyone is going through changes. With footballers, there is the added issue of delayed adolescence. Focusing on a career in football can mean a youngster missing out on some of the normal activities of someone his age.
With the first big contract comes an element of financial independence and the temptation to catch up with his old mates by enjoying some of their pleasures - and so he loses focus at the very moment he needs it most.
For those who star for their country at Under-17 level, there is the added strain of going through this process in public. Some careers can be pushed too fast.
An obvious example is Lulinha, a Brazilian attacking midfielder who gave a masterclass in finishing and broke all scoring records in the 2007 South American Under-17 Championship. He was quickly thrown into the Corinthians first team at a time when the Sao Paulo giants were in crisis, fighting against relegation. He was unsurprisingly unprepared and unable to be the team's saviour. He has yet to recover.
Alternatively, a player may not get enough first-team opportunities - a common danger if he moves to a European giant and finds himself lost in a massive squad.
Going through teenage changes in a foreign land can be particularly disorientating. But Manchester United appear to have done a sound job with the Da Silva twins.
Rafael and Fabio have settled well at Old Trafford. Photo: Getty Images
In their case, there was a compelling reason for bringing them across the Atlantic so early. In Brazil, they would not have been taught how to defend. Indeed, this is almost certainly one of the reasons that Rafael has been able to make more progress than brother Fabio, captain of Brazil's Under-17s and, along with Lulinha, the star attraction.
Fabio played much more from left-back than at left-back, popping up frequently in the penalty area. It has surely been easier for the less flamboyant Rafael to adapt his game to the demands made of a United full-back. It could be that Fabio's long-term future will be as a wide midfielder.
Either way, United must surely be happy with their investment. Buying the Da Silva twins was clearly a good bit of business. A few years will have to pass before we can judge whether Chelsea have hit the jackpot with Piazon.
Comments on the piece in the space provided. Questions on South American football to email@example.com, and I'll pick out a couple for next week.
From last week's postbag:
Q) What effect, if any, did the mass migration of top Brazilian talent to Europe starting in the 1980s have on Brazilian football? Did it impact on the culture, the tactics or the quality of the league?
A) It certainly saw the quality drop, although I also think it led to an increase in tactical experimentation. If you didn't have top players to tip the balance, you would have to find some collective way to do it. It also made life hard for the big clubs. With the quality forced down, it was possible for little teams like Sao Caetano to come from nowhere and beat the big boys. Only penalties stopped them winning the Libertadores nine years ago. Being a big club could be a problem. Pressure was piled on by the fans but the squad was not strong enough to cope with the expectations. Over the next few years, I expect to see the opposite happen. With more money and more top players around, I think the big clubs will be better equipped to put distance between themselves and the rest.