Tis the NBA playoff season, or the time of year when NBA observers enthusiastically draw sweeping conclusions from very tiny samples.
Here are a few thoughts to keep in mind as we all watch playoff basketball over the next two months:
1. As I noted last May, NBA players are essentially working for free in the playoffs. Players have already received their salaries for the year. The monetary reward from the playoffs comes from a) the NBA’s playoff pool (which is quite small relative to the salary many players receive) and b) the potential for a better contract down the road (and I am not sure the playoffs is that important for most free agents). So when you see players give their all in April, May, and June, remember, they are not really being paid to do this. These players are really trying hard because they really like playing basketball (and of course, winning).
2. Playoffs are for fun, not for science. Last year the Golden State Warriors defeated the Dallas Mavericks. It was quite clear from the 2006-07 season that the Mavericks were the better team. But in one week a player(s) and team can play much better (or worse) than expected. This doesn’t “prove” that the winning playoff team is better. In sum, a small sample is not going to trump a large sample.
3. Despite point #2, announcers and sportswriters are going to declare each winning team to be the greatest. And each losing team is going to have obvious holes that need to be filled. The role of luck and chance are, as a rule, generally ignored.
The Best Celtics Team Ever
The playoffs are believed to identify the best NBA team. But as noted, the regular season is a better sample than the playoffs. And when we look at the regular season we already know the identity of the best team in the NBA. And that team is the Boston Celtics.
The Celtics had a truly historic season in 2007-08. How historic? Last June I wrote a column examining the Best Team for Each Team.
In this column was the following table:
We can measure efficiency differential (offensive efficiency minus defensive efficiency) all the way back to 1973-74 (which I have done). With data in hand we can determine the best team in the history of each franchise (at least back to 1973-74). For example, the best Celtics team – prior to this season — was the 1985-86 edition that posted a differential of 8.94. This year the Celtics had a differential of 10.95. This mark easily tops anything we have seen by Boston since 73-74. And given the scoring differential of the teams prior to this date, I think the efficiency differential we saw this year was the best mark in franchise history. Yes, the Celtics with Kevin Garnett, Paul Pierce, Ray Allen (and Rajon Rondo, Kendrick Perkins, James Posey, Leon Powe, etc…) is the best team in this historic franchise’s history.
Of course some will say, “when this team wins a title (or three), then they can rank among the greats in Boston history.” And to those people I say, “No, no, no. Did you not read the first part of this column? The sample from the playoffs does not trump the sample from the regular season. And the regular season sample we have from Boston trumps every other regular season sample we see in this team’s history.”
And I will add… even if Boston falters in the playoffs, this team is still the best in franchise history. Again, the regular season sample is better than the playoff sample.
Other Best Teams
By the way, the Celtics are not the only franchise to post their best mark in team history in 2007-08. The following teams also offered their best this year:
Detroit Pistons (8.17 differential trumps the 7.40 mark seen in 2005-06)
New Orleans Hornets (5.70 differential trumps the 3.47 mark seen in 1994-95)
Toronto Raptors (3.11 differential trumps the 2.37 mark seen in 2000-01)
Two other teams came close to setting a franchise best record. The Denver Nuggets had a mark of 3.70 in 1987-88. This year their differential was 3.59. And Houston had their best differential last year. This year’s differential of 5.02 fell just a bit short of the 5.19 mark we saw in 2006-07.
And for those who are interested, here is every team’s efficiency differential this year.
Tomorrow I am going to tell another story from the regular season sample that just concluded. This story is going to focus on the NBA’s worst.
A WoW Contest (sort of)
Let me close by announcing “sort of” a WoW Contest (and I will explain the “sort of” part in a moment). I would like to know which announcer and/or sportswriter reaches the most dramatic conclusion in the playoffs from the smallest sample.
In the comments, please post your observation. The “best” observation will win… okay, nothing. I don’t have anything to give away. That’s why this is only “sort of” a contest. I will try and note the winner in a forthcoming column (yes, that’s not much of a prize, but it’s all I got).
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.