Finding A Magic Bullet Stat To Prove The Spurs Are Contenders

"Honestly, Tim, the numbers show that we're pretty good. I'll walk you through the math after the game."

Introduction

After a four-year title-drought in the postseason, most Spurs fans find themselves in one of two camps: those who deal with vicarious performance anxiety, and the others who throw themselves into eager anticipation of regained glory. Some of us seem overconfident about the Spurs title chances, citing a mishmash of reasons for inevitable triumph that may only be rational or compelling to ourselves. Others appear helplessly engaged in the worrywart syndrome, constantly focused on things that could go wrong in a subconscious effort to protect ourselves from potential disappointment. I often sense that I'm all over this spectrum, but probably lean most consistently to the anxiety side of the ledger. So I've been searching for a way to become a bit more at peace with the journey, in order to maximize my appreciation of this season whether or not it yields a 5thbanner hanging high and proud at the AT&T Center.

But I can't easily put myself more at ease, because I'm extremely competitive, hyper-analytical, and feel keenly aware of even the slightest Spurs weakness. To me, it's far too unsettling to merely rely on subjective forms of evaluation to arrive at a sound judgment concerning the real title chances of any one team. Perhaps, I thought, there is a central metric or some common theme that appears to elevate a small and select fraction of teams to true contender's status. If I could find that, and see more clearly where the Spurs truly stand, maybe I could enjoy the journey with a bit less angst along the way.

So what is the most elemental aspect of what it takes to produce winning performance at any game that keeps score? Well, the most simple and logical answer would be to consistently score more points than your opponent does throughout a full season of play, and by a large enough average margin that you'd even end up winning some games that you would have lost without this additional cushion. With that in mind, if we look at just one key team statistic that would best predict future performance, how about point differential? In other words, on average, by how much does a team outscore its opponents over a given period of time? Though this basic metric is useful, it does not take into account how efficiently a team scores, and how efficiently it prevents its opponent from scoring. And since a certain fraction of victories occur by the slightest of margins, an efficiency differential seems like it would add a small but perhaps meaningful amount to the predictive power of point differential.

Methodology

The only stat I know of that will give me team offensive and defensive efficiency numbers over a reasonably significant period of seasons is offensive rating (ORtg.) and defensive rating (DRtg.). So I decided to run a query at basketball-reference.com, covering the period between the 1979-80 season (the 1st year of the 3-point shot) and the current season, 2011-12. But first I had to decide on a few basic parameters. I looked at the title winners during that 32-year period. None of them had an ORtg. below 102, and none of them had a DRtg. above 108, so I excluded teams that fell outside that range. I also noticed that none of the title winners during this 32-year span had a win-loss percentage below .570, so I left those teams out as well. And finally, of the teams that came up in the query, I subtracted their DRtg. from their ORtg. to come up with their ORtg./DRtg. differentials.

I also noted that only one team out of the 32 title winners was ranked below 8th in ORtg./DRtg. differential in a given season, and that was the 1994-95 Houston Rockets. Thus, I decided to do differential rankings for each season only ranked through the top eight, that is, if eight teams or more in fact qualified after filtering through my parameters.

Below are the differential results for the last 32 completed regular seasons, plus the current season, where obviously a champion has not yet been crowned. The title winner from the 1979-80 season, through the 2010-11 season is highlighted in bold.

NBA - 1979-80 to 2011-12 ORtg./DRtg. Differentials

1979-80
1980-81
1981-82
1982-83
1983-84
Celtics – 7.5 Sixers – 7.5 Celtics – 6.3 Sixers – 7.4 Celtics – 6.5
Lakers – 5.8 Bucks – 6.9 Sixers – 5.7 Lakers – 5.3 Bucks – 4.2
Sonics – 4.6 Celtics – 5.8 Bucks – 5.4 Celtics – 5.1 Knicks – 3.9
Sixers – 4.0 Suns – 5.2 Lakers – 4.7 Suns – 5.0 Lakers – 3.6
Bucks – 3.9 Lakers – 3.7 Sonics – 4.1 Bucks – 4.4 Blazers – 3.5
Suns – 3.4 Spurs – 2.8 Spurs – 2.3 Spurs – 3.5 Sixers – 2.2
Kings – 3.0 Knicks – 1.6 Sonics – 3.1
Hawks – 2.9
1984-85
1985-86
1986-87
1987-88
1988-89
Lakers – 7.1 Celtics – 9.2 Lakers – 9.1 Lakers – 5.8 Cavs – 7.7
Bucks – 6.9 Bucks – 8.7 Hawks – 7.4 Pistons – 5.2 Suns – 7.4
Celtics – 6.5 Lakers – 7.5 Celtics – 6.7 Mavs – 4.5 Lakers – 7.1
Sixers – 4.0 Rockets – 2.5 Bucks – 3.9 Blazers – 4.4 Pistons – 6.1
Rockets – 1.6 Hawks – 2.3 Pistons – 3.4 Nuggets – 3.8 Jazz – 5.1
Sixers – 2.3 Hawks – 3.7 Hawks – 5.0
Nuggets – 1.2 Jazz – 3.7 Bucks – 3.7
Bulls – 3.5 Knicks – 3.6
1989-90
1990-91
1991-92
1992-93
1993-94
Lakers – 7.0 Bulls – 9.4 Bulls – 11.0 Sonics – 7.4 Sonics – 9.6
Suns – 6.9 Blazers – 8.5 Blazers – 7.2 Bulls – 6.8 Knicks – 7.5
Pistons – 6.4 Lakers – 7.1 Jazz – 6.6 Cavs – 6.7 Spurs – 5.8
Blazers – 6.1 Suns – 6.5 Suns – 5.9 Suns - 6.6 Hawks – 5.5
Jazz – 4.9 Celtics – 5.9 Knicks – 4.1 Knicks – 6.4 Suns – 4.9
Celtics – 4.1 Spurs – 4.5 Celtics – 3.8 Rockets - 4.4 Rockets – 4.5
Spurs – 3.5 Rockets – 4.5 Spurs – 3.4 Blazers – 3.1 Jazz – 4.5
Mavs – 0.0 Pistons – 3.6 Pistons – 2.2 Spurs – 2.8 Cavs – 4.3
1994-95
1995-96
1996-97
1997-98
1998-99
Jazz – 8.6 Bulls – 13.4 Bulls – 12.2 Lakers – 8.2 Spurs – 9.0
Sonics – 8.5 Sonics – 8.2 Jazz – 9.6 Sonics – 8.0 Jazz – 7.4
Magic – 7.3 Jazz – 7.2 Sonics – 8.5 Bulls - 7.9 Blazers – 7.1
Spurs – 6.3 Spurs – 6.7 Heat – 6.2 Jazz – 7.3 Heat – 5.8
Bulls – 5.2 Magic – 6.0 Hawks – 6.2 Pacers – 6.8 Pacers – 4.3
Pacers – 4.0 Lakers – 4.8 Pistons – 6.2 Suns – 5.6 Lakers – 3.3
Bobcats – 3.5 Pacers – 3.6 Lakers 4.6 Heat – 5.6 Pistons – 2.9
Knicks – 3.4 Cavs – 3.2 Blazers – 4.6 Spurs – 4.4 Magic – 2.9
Rockets – 2.3
1999-00
2000-01
2001-02
2002-03
2003-04
Lakers – 9.1 Spurs – 8.6 Kings – 7.9 Mavs – 8.4 Spurs – 8.1
Blazers – 7.1 Kings – 6.0 Lakers – 7.7 Kings – 6.8 Pistons – 6.8
Spurs – 6.4 Jazz- 5.2 Spurs – 6.8 Spurs – 5.9 Pacers – 6.6
Suns – 5.6 Blazers – 4.7 Nets – 4.5 Nets – 5.7 T-Wolves – 6.4
Jazz – 5.0 Sixers – 4.7 Mavs – 4.5 Pistons – 4.2 Kings – 5.4
Pacers – 4.9 Mavs – 4.5 T-Wolves -3.7 Pacers – 3.8 Mavs – 4.7
Heat – 3.5 Bucks – 4.2 Blazers – 3.4 Blazers 2.9 Lakers – 4.2
Bulls – 2.9 Lakers – 3.6 Pistons – 2.4 Jazz- 2.7 Grizzlies – 2.6
Celtics – 2.4
2004-05
2005-06
2006-07
2007-08
2008-09
Spurs – 8.7 Spurs – 7.7 Spurs – 9.3 Celtics – 11.3 Cavs – 10.0
Suns – 7.4 Pistons – 7.7 Mavs – 8.1 Pistons – 8.5 Celtics – 8.2
Heat – 7.1 Mavs – 6.8 Suns – 7.5 Lakers – 7.5 Lakers – 8.1
Mavs – 6.2 Suns – 5.7 Rockets – 5.3 Jazz – 7.3 Magic – 7.3
Rockets – 4.5 Grizzlies – 4.3 Bulls – 5.3 Magic – 5.8 Blazers – 6.1
Pistons – 4.4 Heat – 4.2 Pistons – 4.7 Hornets – 5.8 Rockets – 4.4
Nuggets – 2.1 Cavs – 2.4 Cavs – 4.2 Rockets – 5.2 Spurs – 4.2
Clippers – 1.7 Jazz – 2.9 Mavs – 5.0 Nuggets – 3.8
2009-10
2010-11
2011-12**
Magic – 8.1 Heat – 8.2 Bulls – 9.1 - out
Cavs – 7.1 Bulls – 8.0 Spurs – 7.1
Jazz – 5.7 Lakers – 6.7 Thunder – 6.6
Spurs 5.5 Spurs – 6.2 Heat – 6.4
Hawks – 5.2 Celtics – 5.9 Hawks – 3.7 - out
Lakers – 5.1 Magic – 5.9 Pacers – 3.6
Nuggets – 4.3 Nuggets – 5.0 Nuggets – 3.0 - out
Celtics – 3.9 Mavs – 4.7 Celtics – 2.8
Clippers – 2.8

Special Notes, 2011-12 season:
** Did not make top-eight in differential (Grizzlies, 10th, Lakers, 11th)
*** Did not qualify top-eight in differential (Sixers (5th) - disqualified for not meeting W-L record threshold)

Conclusion

The basic idea of this exercise was to look more carefully over a good chunk of NBA history, and see if a central metric (ORtg/DRtg differential) to team success during the regular season could be used to give a better sense of a team's chances to win a title that year. So first off, let's look at some summary stats gleaned from the above differential data.

  • The median differential for title winners over the last 32 years is 6.8 (for the 2011-12 Spurs, it's 7.1).
  • Excluding one outlier at each end, the range in differentials for title winners is between 3.6 and 12.2.
  • 59.4% of all title winners were ranked in the top two in differential.
  • 75% of all title winners were ranked in the top three in differential.
  • 81.3% of all title winners were ranked in the top four in differential.

If you look at the differentials for this season, you'll notice a few things:

(1) The Spurs are ranked second, and are the highest ranked still in the playoffs. There's also evidence that the Spurs differential was increasing heading into the playoffs.

(2) Though the Lakers squeezed by Denver in round one, history is not on their side in terms of securing another title this year. They would be the lowest ranked team in differential (11th) to do it over the last 33 seasons.

(3) Under 10% of title winners over the last 32 years were ranked 8th or 9th in differential. As a result, a championship this season does not look too promising for the Celtics and Clippers.

(4) The Sixers would by far have the lowest winning percentage of any title winner in the last 33 years, and they don't have Hakeem Olajuwon. As a result, their chances in my view are essentially nil.

(5) That leaves the Spurs, OKC, Miami, and Indiana, with the Pacers as obviously the long shot.

Now, can this type of data predict a title winner? Not at all. Nevertheless, for me it does serve to add further clarity as to where the Spurs stand in their 2011-12 quest for a 5th title in the past 13 years. And I have to say, my anxiety level concerning their title prospects has dropped noticeably from doing this exercise. I'm now ready to enjoy the rest of the postseason, and with more optimism than ever before.

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