I haven't done the research, but I'm wondering how it would correlate between those that win a junior Slam at 16, 17, and 18 years old - if the younger guys tend to have more success translating to the ATP tour or not. I have no idea, but that logic basically holds for the ATP: The players who tend to break into the top 100 at 17 or 18 tend to be better than the guys that make it at 19-20 -- as a general rule. Presumably a 16-year old junior champion is, in terms of precedent, a safer bet than an 18-year old, but who knows.
As for Lee/Hewitt, I agree that nothing wowed me, but then again they are 16 and 17, respectively, and I don't feel capable of assessing junior talent. Let's see how they look a year or two from now. Similarly with Kouame...he actually
did impress me a bit in that he reached the 3rd round of a Grand Slam at just barely 17 years old, and took #36 Alejandro Tabilo to four sets.
But it is also all-too-easy to get over-excited about really young guys, without remembering that "greatness talent" is quite rare. I mean, consider:
- Jannik Sinner became the 16th player to win 5+ Grand Slams in the Open Era
- Alexander Zverev became the 60th Grand Slam winner of the Open Era
- Only about 140 players have won a big title
If we take 5 GS as the cut-off for true ATGs, then an ATG is born every four years or so, a Grand Slam winner every year or so, and about two big title winners per year. Carlos Alcaraz is the youngest ATG, born in 2003, which means that as an average with a +/- range of two years, the next one will be born in the 2005-09 range. That would be the window of not only Mensik, Jodar, and Fonseca, but also Tien, Landaluce, Kouame, Hewitt, and a ton of other guys. Lee was actually born in 2010, crazily enough.
Maybe all of these young guys turn out to be pretty good, though the majority of them will max out somewhere in top 10 to 100, but I think it is safe to say that of all those players born in the 2004-10 range, only one or two them are likely to become all-time greats. A half dozen might win Slams, and maybe a dozen or a bit more win big titles. That's the "historical precedent math," at least.