In years like this one when college basketball is full of enticing NBA prospects, many NBA teams seem to throw away their seasons in an attempt to receive a higher pick. General Managers trade away their best players before the season begins (the 76ers and Celtics last summer are both great examples), teams allow some of their best players to leave in free agency (such as the Utah Jazz last summer), and some teams have key players miss games for suspicious injuries (I seem to recall the Warriors employing this tactic a couple years ago). The strategy is certainly tempting when you consider how the right draft pick can alter the course of a franchise. The Spurs have been arguably the best franchise in basketball since drafting Tim Duncan; Lebron took the Cavaliers to the finals just four years after the team finished 17-65. But these are the success stories. Other teams continue to struggle even though they get a high lottery pick every year. So is tanking worth it? What is the expected value of getting a higher draft pick?
As I mentioned in my “Best & Worst NBA Draft Classes” post, I have assembled a large data table with stats for each player taken in the lottery in the past 25 years. I will be using win shares (WS) and win shares/48 (WS/48) to measure the overall success of a player. WS approximates the overall value of a player, while WS/48 approximates the overall value of a player per 48 minutes played (please see the previous post if you need a little more explanation on these stats). Because we are trying to determine the expected value of each pick in the lottery, we will be looking at the average stats of every player chosen in that slot over the past 25 years.
The charts below illustrate the average statistics of a player taken at a certain spot in the lottery. The X-axis is the pick number and the Y-axis is the average statistic for a player selected with that pick. (Click on a chart to see a magnified version)
Several interesting facts emerge from these charts. The first pick in the draft has an expected value that far exceeds any other pick. Picks 2-5 are nearly identical. Surprisingly, pick 6 has one of the lowest expected values of the entire lottery, and picks 7-8 aren’t much better. However, players picked 9th have an expected value nearly equal to players picked 2-5 (if you look at WS/48). After the 9th pick, the expected value gradually declines, except for another unexpected increase at pick 13. (Lest you think that Kobe being picked 13th is skewing the data, I tried taking his stats out of the equation and the result wasn’t much different.)
Let’s look at the data a little differently. The following charts show the percentage decline from one pick to another. For example, both charts show that a player picked second has an expected value that is about 20% less than a player picked first. A negative percentage means that a player drafted in that spot actually has a higher expected value than the player selected one spot previously.
Both charts show similar results, but for simplicity’s sake, let’s just refer to the WS/48 chart for a moment. *If the end of the season is near and your team has the 6th worst record in the league, you may want to lose a few extra games because moving from the 6th pick to the 5th pick increases the expected value of your pick by nearly 30%! However, if you already have the 5th worst record, the chart shows that moving from the 5th pick to the 4th pick will only increase the expected value of your pick by about 2%. The answer to whether tanking is worth it depends on where you expect to fall in the lottery. Getting a top 5 pick is very valuable, but pick 6 isn’t noticeably better than pick 14. And the 14th worst team got to enjoy a season in which it nearly made the playoffs, while the 6th worst team endured an excruciating season (unless you’re a Bobcats fan, who would consider a 28-54 season a raging success!)
* My analysis here ignores some of the complexity of the lottery system. The worst team in the league isn’t given the first pick; it is merely given the highest probability of receiving the first pick. A team that is tanking needs to consider whether it is worth losing more games in exchange for the mere probability of the highest pick. On the other hand, the lottery is structured so that a team can confidently predict what range its pick will fall into. For example, the worst team in the league is assured of receiving a top four pick. For more information about how the lottery works, look here: http://en.wikipedia.org/wiki/NBA_draft_lottery.