Yes, which is why I said "true." My re-framing was based on the idea that you can't just pick all teenagers and project them forward. For example, in 2010 the top ranked player age 20 and under was Ricardas Berankis at #87. He's pretty much been a lower top 100 player since. There are many other such examples.
That said, the point of this thread is to talk about young players who have a chance to be very good, even great. All the names I mentioned have potential.
But it is interesting to consider what makes a talented young player blossom and what leads to stagnation. A player I've been touting for awhile is Andrey Rublev, whose game I just like. But he's been very stagnant this year and now I've had to temper expectations, to the point that I really question whether he has that "X-factor" needed to succeed.
Finally, as I've mentioned in various blog articles, there are some significant benchmarks to keep an eye out for. For instance, top 100 before turning 19. Not every such player turns into a star, but a good percentage do.
By way of example, of players born in the 80s, 21 reached the top 100 as 18-year olds. I think 21 players is large enough of a sample size to be, if not definitive, at least meaningful. Here are how those 21 breakdown:
3 became all-time greats (6+ Slams): Federer, Nadal, Djokovic
3 became multi-Slam winners (2-5 Slams): Safin, Hewitt, Murray
2 became single Slam winners: Roddick, del Potro
3 won at least a Masters: Robredo, Coria, Berdych
6 became good players: Youzhny, Ancic, Monfils, Gasquet, Gulbis, Nishikori
4 didn't amount to much: Vinciguerra, Acasuso, Korolev, Young
To put that another way, about two-fifths (38%) won at least a single Slam, more than half (52%) won at least a Masters, and 81% had at least good careers. Only 19% were flops.
Here are the players in the 90s that have reached the top 100 as 18-year olds (so far): Tomic, Chung, Coric, Zverev, Fritz. Tiafoe is on the cusp and should get there. Shapovalov has tons of time and barring major set-backs will get there. A few others have outside chances: Kozlov, Rublev, Lee, Tsitsapis, etc. Of the five who have made it so far, I would guess that Zverev and Fritz will be Slam winners, Coric and Tomic will be (is already, for Tomic) top 20 types ("good") and Chung will disappoint. So that would be very similar percentages.
As a side note, it looks clear that far fewer players born in the 90s will reach this benchmark. This breaks from historical precedent, as by my count, 20 players born in both the 60s and 70s reached the benchmark. Even given that I may be missing one or two players in each decade, that is remarkable consistency. But among players born in the 90s, it looks like anywhere from about 6 to 10 will accomplish the feat. I'm not sure the same rough percentages will hold up; maybe that there are fewer indicates that it is more rarified, and thus the players that do reach this benchmark could be better.
