Dave Berri is the General Manager of the Wages of Wins Network. He is a Professor of Economics at Southern Utah University, lead author of both “The Wages of Wins” and “Stumbling on Wins”, and past president of the North American Association of Sports Economists.
The Difference in Differential
In my last post I noted that the NBA has not historically had much competitive balance. This is true when you look at each season. And it is true when you look at franchises over time. About half of all NBA teams have never won a title. Furthermore, when we look at regular-season efficiency differential (offensive efficiency minus defensive efficiency) we see that the story of each team’s best and worst is quite different.
For example, consider the Clippers and the Lakers. Both teams currently play in the same market. But outcomes for each team have been quite different. The Clippers best efficiency differential was 1.94. That happened in 1974-75 when the Clippers were called the Braves and the team played in Buffalo. Since 1973-74 (the first year we can calculate efficiency differential in the NBA), the Lakers have bested the 1.94 mark of the Braves in 1974-75 in 29 different seasons. In other words, the Clippers-Braves at their best would be a very bad season for the Lakers.
A similar story can be told about the San Antonio Spurs and Denver Nuggets. Both teams were originally part of the ABA. And one of these teams – and yes, it was the Nuggets – was quite successful in the ABA. More recently, the Spurs have had quite a bit of success. As for the Nuggets…
The 2011 NBA Season Team Efficiency Differentials
The following table reports each team’s efficiency differential in 2010-11. It also reports how that mark ranks in franchise history. We see in the last two columns where the 2010-11 result ranks when we consider the best seasons first. We also see – in the last column – how this last season ranks when we consider the worst seasons first.
As one can see, two teams posted all-time best marks in 2010-11. The Miami Heat didn’t quite do everything their fans hoped for last year. But the Heat did lead the NBA in efficiency differential in the regular season. And the mark posted by the Heat this past season was the best mark in franchise history. So in that sense, the acquisition of LeBron James and Chris Bosh paid off.
The other team to set a franchise record for efficiency differential was the Denver Nuggets. Denver’s efficiency differential when Carmelo Anthony was traded was only 2.46. So the Nuggets managed to set their franchise record because of how the team played without Melo.
One should note – and those familiar with Denver’s history would know this — that the Nuggets did post a better efficiency differential the last two seasons the team played in the ABA. And at that time – judging by the performance of ABA and NBA teams in exhibition games – the ABA was at least as good as the NBA. From 1973 to 1975, the ABA and NBA played 96 exhibition games and the ABA team prevailed 62 times.
Once Denver came to the NBA, though, the Nuggets generally struggled. To put that struggle in perspective, Denver best efficiency differential in the NBA (again, seen in 2010-11) was bested by the Spurs 15 times since 1976, including during this past season.
The Best of Each Team
Once again, each franchise at its best is not at the same level. To see this point, consider the best marks of each franchise since 1973-74 (see below).
A few items stand out from this list.
- Only 13 teams led the NBA in efficiency differential the same year where the team posted the franchise best mark.
- Ten franchises have never reached the 6.0 mark. In 2010-11, four teams – the Heat, Lakers, Spurs, and Bulls – reached the 6.0 mark. What we saw from the Bulls, Spurs, and Lakers in 2010-11 did not rank near the best mark of these franchises. In fact, both the Spurs and Lakers have surpassed the 6.0 mark at least 10 times.
- Like the Nuggets, the Nets posted better marks in the ABA. Specifically, in 1974-75 the Nets posted a 7.1 differential. The Nets also won the last ABA title in 1976. Soon after, though, the Nets sent Dr. J. to the Sixers and the Nets have never been as good again.
The Worst of Each Team
In closing, let me post one last table. Here are the worst teams in the history of each franchise. No team posted their franchise worst mark in 2010-11. Washington, Cleveland, and Charlotte posted their second worst mark this past season.
When we look at this last table we see that the Lakers and Suns – at their worst – are not nearly as bad as other franchises respective low points. Both of these franchises have posted their worst differential at a level better than -5.00. Surprisingly, a similar story can be told about the Charlotte Bobcats. In sum, Charlotte has never been that good. But so far, the Bobcats have not been as horrible as other franchises. I’m not sure that is much to get excited about. However, it does sound like something for MJ’s team.