To project the NBA's top 99 players in 2015, it's important to consider which players are considered the NBA's top players now. With that information, you can look at where they were in their careers five years ago and see what trends appear.
While there are many different ways to compile such a list statistically, even the most advanced statistics can't fully capture a player's value. So for our purposes, the Top 100 lists painstakingly made by SI's Zach Lowe and the CBS Sports basketball team over the summer are more than adequate a data set.
A total of 112 players appear on one of the two lists, and while there might be room for objections on the margins, it's hard to argue that those 112 aren't a representative sample of the NBA's elite. It's certainly a big enough sample for some extremely interesting trends to emerge:
Basketball, with an arduous 82-game season and its emphasis on rapid cuts and lateral mobility, is a young man's game. Weighted by minutes played, the average age of an NBA player was 26.6 years old. That's true even amongst the game's elite, as the average age of the top 112 players is 26.35.
Attributing the success of older teams like the Dallas Mavericks and the Boston Celtics to age is a classic case of confusing causation with correlation: they are good not because of their age, but because it takes an incredible amount of talent to stay in the league for over a decade.
There were only 17 players among the top 112 who were 32 or older last season. Twelve had made an All-NBA team before. Some -- Kobe, Dirk, Duncan -- remained All-Star level players, but others -- Jason Kidd, Grant Hill, Shawn Marion -- had enough talent to make up for their declining athleticism and become effective role players. There are a handful of exceptions (Shane Battier, Stephen Jackson, Marcus Camby, Jason Terry, Andre Miller), but transcendent players seem much more likely to remain effective as they age.
The implication for the 2015 list is clear: most of today's effective 27-and-older players shouldn't be on it. Solid second-tier players like David Lee, Andre Iguodala and Emeka Okafor are more likely to be on their way out of the league than they are to keep their current position amongst the NBA's hierarchy. To stay in the top 100, they will have to compete with more talented players like Dwyane Wade and Pau Gasol undergoing a similar physical decline as well as the huge wave of younger players behind them.
A little over half (58) of the top 112 players in 2010-2011 were under the age of 22 in 2006-2007. Almost a third (31) weren't even in the NBA: many were in college or overseas and some (Blake Griffin, John Wall) were still in high school.
Jrue Holiday and DeMarcus Cousins were 16 in 2006. Tyreke Evans and James Harden were 17 and Russell Westbrook and Kevin Durant were 18. In all likelihood, there are high school sophomores and juniors today who will be among the league's top 100 players in 2015.
The scary part, depending on your perspective, is we already know who they are. High-school recruiting rankings, for all the negative press they get, are quite accurate at identifying elite basketball players once their age cohort passes puberty. Thirteen of the today's top 112 were in American high schools in 2006; all were consensus five-star recruits. Only two (Griffin and Harden) weren't ranked in the top 10 in their high school class.
That doesn't mean the top players in the class of 2011 (Duke-bound Austin Rivers), the class of 2012 (6'6 wing Shabazz Muhammed) or the class of 2013 (6'5 guard Andrew Harrison) are shoe-ins to be on the 2015 list. The careers of many seemingly can't miss five-star prospects, from .L.A Lakers reserve big man Derrick Caracter to Golden State Warriors second-round draft pick Jeremy Tyler and former Illinois swingman Jereme Richmond, were derailed as they got older, often due to off-the-court issues.
It does explain why so many go astray: they are teenagers who have a good shot at being worth tens of millions of dollars in five years, and everyone around them knows it. Yet due to the NCAA's amateurism rules and the American system of youth development, they can't accept any monetary compensation for their talents. These players, especially the ones from broken homes, are easy targets for unscrupulous middle-men. We don't know which one of today's five-star recruits will survive this gauntlet, but history tells us some will.
If the career trends of today's top players are any guide, they will be joined on the top 100 list of 2015-2016 by a lot more younger guys and a lot fewer older ones than we, writing from the perspective of 2011, imagine.