OK, so basketball isn't as in love with its records as some other sports — most notably baseball.
Therefore it's just off the radar screen that a number of today's players are making a bid to become the NBA's record holders in career stats. That's partly because so many players in today's game turned pro directly out of high school, or after just one year of college. Kevin Garnett, Kobe Bryant, Dirk Nowitzki, Allen Iverson, Carmelo Anthony, LeBron James and others have opportunities to take over several long-standing career records.
So, we started to wonder: Will they get there?
To estimate a player's odds of breaking a record, I created a metric based on his age, height and established performance level. This method cribs liberally from the "Favorite Toy" formula developed by Bill James for baseball a couple of decades ago. No, I don't know why he called it "Favorite Toy" either, but for baseball, the thing works.
For basketball, it requires some modification. For starters, we have to allow for the fact that NBA careers are slightly shorter than baseball careers. Second, we have to allow for the fact that height is an important predictor of career length, with every inch of deviation from the optimal height of 6-foot-10 reducing a player's expected number of career games.
Through some experimentation, I developed a basketball version of the "Favorite Toy."
The first step was to figure out how much longer a player could be expected to play at, on average, his current level.
Here is the equation:
Remaining seasons = (42-Age)/2.2
"Age" in this case is the player's age in years as of Dec. 31, 2008. This gives a 22-year-old 9.1 seasons remaining, a 28-year-old 6.4, and a 36-year-old 2.7.
I should point out these estimates are wildly optimistic for most NBA players, but for this project, we aren't looking at "most" players — we're looking at the stars, who tend to have the longest careers.
Note: This is not a prediction of when a player will retire. Rather, it's a way to estimate the number of future seasons for which to credit a player in the formula below.
As a second step, I factored in height using this equation:
Adjusted Remaining Seasons = Remaining Seasons * (60-HeightDiff)/55)
"Remaining Seasons" is the prediction from the first equation above, and "HeightDiff" is the difference in inches from the optimal height of 6-foot-10.
As a third and final step, we need an "established level" for a player in each statistical category. That's the easiest part, because the Bill James formula translates perfectly to basketball for this measure.
To find a player's "established level" of play, we use the most recent three seasons of data, with the most emphasis placed on the current season:
• Take one part of the player's results from two years ago; • take two parts of his results from last season; • take three parts of his prorated results from this season; • add it all up; • divide the sum by six.
Note: The "Favorite Toy" is ideally employed between seasons. In this case, we are using the current season's data because the regular season is about 80 percent finished.
For example, Nowitzki is on pace to play 3,011 minutes this season. He played 2,821 minutes last season, and 3,089 the year before, so for the purposes of this discussion his "established level" is 2,960.7 minutes.