Wins Produced was developed as a method to assign the credit (and blame) for what we see at the team level in basketball to the individual players (such a method is important for some research in sports and economics). We know how much a team has won. What we want to know is which players were responsible for that outcome.
For example, consider the Chicago Bulls last season. The Bulls finished the 2007-08 season with 33 victories. When we look at Wins Produced – reported in Table One — we see that Luol Deng’s 6.0 Wins Produced led the team. Ben Gordon – who led the team in scoring (and his agent used this fact to demand a significant increase in pay) – only produced 2.7 wins. In essence, Deng was twice as productive as Gordon.
Although this observation is interesting (or not), when we look at this particular team we have to ask a more important question:
What the hell happened last year?
In 2006-07 the Chicago Bulls won 49 games, which is pretty good. The team’s efficiency differential (offensive efficiency minus defensive efficiency), though, was 5.2. Such a mark is consistent with a 54 win team (which is even better).
Virtually all of these 54 Wins Produced could be traced back to players who Chicago employed in 2007-08. Additionally, the Bulls added Joakim Noah. Given what Noah did in college it was expected that he would contribute as a rookie. And as Table One indicates, Noah was above average in 2007-08.
When you add an above average rookie to the collection of veterans Chicago employed in 2006-07, it’s not a stretch to state (as I did last September): … just looking at what this roster did in the past – which is a good but not perfect predictor of the future in the NBA – Chicago fans should expect a team that surpasses 54 wins. And that means the Bulls – or Da Bulls – have returned.
After the first month of the 2007-08 NBA season, though, it was clear that something was wrong in Chicago. The team’s record after November was only 3-10. The team’s efficiency differential was -8.5, a mark consistent with a very bad team.
Back in December both John Hollinger and I (in separate columns) noted the problem. Chicago was not hitting its shots. To illustrate this point I produced three projections of Chicago on December 1, 2007.
Here is how these projections were summarized last fall: … had each Chicago player maintained what they did last year, the Bulls would be on pace to win 57 games. …What happens if all we only utilize shooting efficiency from 2006-07, but keep everything else as it is in 2007-08? Now we see the Bulls would be on pace to win 55 games. Yes, virtually the entire problem this team has is tied to shooting efficiency. If this problem were solved, this team would start winning again.
So after one month, the Bulls problem was identified. The ball was simply not going in the basket that often. Consequently this team was losing.
As GI Joe would say “knowing is half the battle.” Unfortunately when we look at the final numbers for the Bulls, it doesn’t appear the team made much progress on the other half of this battle.
During the 2007-08 season the Bulls fired their head coach. They also were part of a major trade with Cleveland and Seattle that saw the Bulls acquire Drew Gooden, Larry Hughes, Cedric Simmons, and Shannon Brown (for Ben Wallace, Joe Smith, Adrian Griffin, and a second round draft choice in 2009).
Despite all these moves, though, the Bulls didn’t improve substantially. They certainly weren’t able to get back to the promise of 2006-07.
Table Three indicates that given what the veteran NBA players Chicago employed in 2007-08 did in 2006-07 (and this includes the players acquired in mid-season), the Bulls should have expected to win 49.4 games last year. In other words, they should have been as good as they were in 2006-07.
Instead, as noted earlier, the team only won 33 games. Returning to the shooting efficiency story we saw last December…. if Chicago’s returning players managed to maintain the same level of shooting efficiency we saw in 2006-07, Chicago’s projected wins rises to 44. In sum, just as we saw after just one month, Chicago’s problems at the end of the season were stilll primarily tied to a decline in shooting efficiency.
How, Why, and Derrick Rose
It’s important to emphasize that numbers allow you to assign credit and blame. The numbers allow you to see how productive a player has been, and where this productivity has changed. But the numbers are a bit fuzzy on the question of “why”. In other words, we can see the impact a change in shooting efficiency has on the success of the Bulls, but the numbers are not going to tell you why Luol Deng, Kirk Hinrich, Chris Duhon, Andres Nocioni, Ben Gordon, and many of the other players employed by Chicago were not hitting their shots last year as well as they did in 2006-07.
It is apparent when we look at the data that the shooting problem appeared very early in the 2007-08. And it doesn’t appear that this problem was ever fixed. Now the Bulls have drafted point guard Derrick Rose. At this point it’s not clear yet that Rose will help. It’s not even clear that he will be a productive pro (it also isn’t clear yet that he won’t). We should note, though, that despite the shooting woes of Hinrich and Duhon (the latter moved on to New York), each of these veteran players was close to average last season. And rookies tend to be below average. So Rose may not help much immediately. Still, nothing else the Bulls did worked last year. So why not take a shot with Rose?
Beyond the addition of Rose – and loss of Duhon – the Bulls are returning virtually the same team that ended the 2007-08 season. The lone exception might be Ben Gordon, who currently is unsigned.
As I noted earlier, his agent has argued that since Gordon was the leading scorer on the Bulls last year, Gordon should be the highest paid going forward. When we look at Wins Produced, though, it is clear Gordon’s productivity is inconsistent with the money he is demanding. In fact, given Gordon’s lack of production, it’s not clear that the Bulls should even bother signing Gordon to the offer the team has already made. So what should the Bulls do?
One possibility has been offered by Steve Luhm with the Salt Lake City Tribune. Luhm has suggested that Utah offer Andrei Kirilenko and Ronnie Brewer for Gordon. As noted a couple of weeks ago (in a post titled — Note to the Media), Kirilenko and Brewer were well above average for the Jazz last season. So such a suggestion – from a Jazz fan (I suppose) — would definitely help the Bulls (and hurt Utah).
Barring such a trade (which I can’t believe Utah would do), the Bulls will probably enter 2008-09 with Rose and much of the roster that finished 2007-08. If we look back at 2006-07, such a roster could be very competitive. If what we saw in 2007-08, though, is the future for these players, then “Da Bulls” are not going to be seen again anytime soon.
One last note on Gordon…Gordon, relative to 2006-07, was a less efficient scorer in 2007-08. Relative to the other players on Chicago in 2007-08, though, Gordon was one of the most efficient scorers on the Bulls. This fact, though, does not increase Gordon’s value. The proper comparison is not Gordon’s shooting relative to the rest of the Bulls. No, a better comparison is to look at everything he does (including shooting) relative to the average shooting guard in the league. And by that comparison, Gordon should not be the highest paid player on this team (or any other team).
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Our research on the NBA was summarized HERE.
Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:
Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.