Tennis was once, like chess and gymnastics, the province of the child genius. The money that flooded into the sport when the game went professional in the 1970s inspired a wave of teen prodigies to devote their lives and bodies to the game.
Although the women's side became notorious for its cautionary tales of burnout and injury - think Jennifer Capriati, Andrea Jaeger, Tracy Austin, even Monique Viele - the men's game was also regularly brutalized by youth.
Bjorn Borg, John McEnroe, Boris Becker, Andre Agassi, Pete Sampras and Rafael Nadal all reached the upper echelon and, in most cases, won Grand Slams before their 20th birthdays. Even the relatively late-blooming Roger Federer was knocking off Top 10 players when he was 18.
Nadal was the last man, in 2005, to win a major as a teenager; Maria Sharapova was the last woman to do it, at Wimbledon, the previous year. Now breakthroughs are coming at the tail ends of career rather than at the beginnings.
Inconsistency and parity rule on the women's side, and the era of iron-willed children like Steffi Graf, Monica Seles and the Williams sisters has given way to the fragility of Kvitova and 2008 French Open champ turned sporadic basket case Ana Ivanovic.
The biggest hitters win the biggest tournaments, but their accuracy comes and goes; the consistent players like Caroline Wozniacki do well in the rankings but get hit off the court at the majors. To find the next Graf, you would have to put Wozniacki together with Kvitova.
That's a precarious balance to maintain, and it seems to be too much to ask of a young player today. Perhaps the demands of power can no longer be reconciled with the demands of consistency on the women's side.
Young male players face a different problem: A logjam at the top. Rather than racing from out of nowhere straight to the Wimbledon title at 17, la Becker, today's kids take it one baby step at a time.
The last youngish player to win a major in recent years was Juan Martin del Potro, who took home the 2009 U.S. Open title a week before his 21st birthday; injuries have slowed him since. In 2011, perhaps the most talented of the tour's new faces, Grigor Dimitrov, struggled just to leave the minor leagues behind and gain entry into ATP main draws for the first time.
Becker would have scoffed at that promotion, but by today's standards, it counts as a definite step forward. In 2012, Dimitrov might even be able to get out of the first round of a few those main draws.
The sport is getting older. Is that a good thing? There are fewer burnout cases, which is a positive; we're more likely to get a chance to see players through all phases of their careers, rather than watching them walk away or decline early.
But there's still an obvious yearning among fans for prodigies, for the new, for a sense that tennis is dynamic and evolving. The top four men are great, but if their dominance continues, it's bound to feel stagnant at some point.
A lot of excitement was generated at the Australian Open at the start of the year by the seeming emergence of a new ATP generation: Dimitrov, Alexandr Dolgopolov, Milos Raonic, Ryan Harrison and Bernard Tomic. Each of them, like today's top women, would go on to have wildly up and down seasons; inconsistency may be their defining trait as well.
If the prodigy is dead, tennis fans should mourn. The game is at its most exciting when a new player rides in and upends everything, the way Nadal did in 2005, when he went from No. 50 all the way to No. 2, and stayed there. It's very difficult to imagine that happening today, on either tour.
Something important, a sense of renewal and promise and unpredictability, would be lost if tennis is no longer the province of youthful genius.
But hope springs eternal. Last week, the most powerful and successful of the 2011 crop, Raonic, finally returned from a hip injury. He won his first round in Tokyo and then played Nadal. You could feel it for a second, an extra dose of excitement as the upstart tried his luck against the established star.
Then Nadal, the game's last true prodigy, beat him in straights.