Roger Federer and Serena Williams have 17 Grand Slam titles each. Federer has earned more prize money than anyone in the history of tennis. Williams has earned more prize money than any woman in the history of sports.
They have two other things in common. Both are 32, and each finished Wimbledon in tears.
It's tough to win a Slam after 30. Each year the body grows more weary, and the age gap between opponents widens. Meanwhile, the competition creeps closer.
Federer, Williams and Li Na have all won Slams in their 30s. Yet their triumphs skew the evidence. According to an analysis conducted by Nate Silver's FiveThirtyEight, only 10.3 percent of majors have been won by someone older than 29 and just 3.3 percent by a player over 31.
Many players compete after they turn 30. Yet there are so few early '80s babies winning Slams.
FiveThirtyEight analyzed the likelihood of players winning a Slam after age 30. It's unlikely.
John McEnroe and Bjorn Borg were only 25 when they won their last Slam. Mats Wilander won all seven of his Slams by age 24.
If you only include retired players, the mean age of a Slam winner is 25.16. Jimmy Connors reached a semifinal at the U.S. Open at age 39, but he was 31 when he won his last Slam.
Of course, anyone who enters a Slam has a chance to win it. However, most of the players over 30 are long shots.
Only a select few, nearly all already Slam winners, have any serious shot at pulling it off.