Sunday, November 17, 2013

Defense does not always win NBA championships


The old adage goes that “defense wins championships.” You don’t hear it just on the professional level, but anybody who has played an offense vs. defense team sport at any level has heard it. Frequently, however, it’s potent offenses that succeed in the NBA. Whether it’s LeBron James and the Big Three in Miami, Kevin Durant and Russell Westbrook in Oklahoma City, or even Dirk Nowitzki and the Dallas Mavericks, high-powered offenses get media coverage and sell tickets.

So what is really more important to have a successful franchise: offense or defense? Clearly, a combination of both is essential but in this analysis, I’m looking to delve into the idea of seeing which side of the ball is more effective to focus on. To do that, I’m going to focus on two main barometers of success in the NBA: playoff teams and championship teams.

First, here’s a look at the team offense and team defense ratings of every NBA champions from 1991 to 2013.

Team offense and defense ratings of NBA champions relative to the rest of the league. 1991-2013
The best way to read this graph is to follow the graph from a year to year. For example, the 1991 Chicago Bulls had the second-best offense rating in the league and the ninth best defense rating—thus offense was more important that year. Admittedly, there is some wild variation in whether an NBA champion is more of an offensive or defensive threat. The one consistency is that 20 of the 23 champions (exceptions: 2011 Mavs, 2006 Heat, and 1995 Rockets) were top-five offense and/or defenses. In total, 11 of those 23 champions had top-five offenses and 14 of the champions had top-five defenses, so in that light, defenses are marginally more important.

All 16 playoff teams are more difficult to represent graphically in a longitudinal manner, but here’s one way that helps show the trend. In this graph, I’ve taken the difference between the amount of top-16 offenses and top-16 defenses that actually made the playoffs. For example, in 2013, 10 of the top-16 offenses in the league made the playoffs and 13 of the top defenses made the playoffs (represented in this graph by a net value of +3 for three more top-16 defenses than offenses).

Difference between top-16 ranked defenses and top-16 ranked offenses making the 16 NBA playoff spots. 1991-2013

In this light, defense is clearly more important to making the playoffs. In 15 of the 23 seasons represented here, there was at least one more top defense in the playoffs than offense. Only three times (1991, 1992, and 1998) were there more offenses than defenses.

To combine what these two graphs say: defense may get you to the playoffs, but once you’re there, there’s little that can be said about whether a great offense or defense can predict a team to win it all.

This year could provide a very good case study with Miami Heat ranking currently as the most efficient offense (via ESPN’s John Hollinger) and the Indiana Pacers the best defense. A LeBron vs. PG24 matchup in the 2014 NBA playoffs is definitely in the forecast.

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