In terms of winning the NBA championship, the Spurs are having their best season ever--so far! This judgment is based on a simple statistical result that appears to be the best predictor of Spurs championships--the Simple Rating System (SRS) by Basketball-Reference.com. ESPN's John Hollinger's analyses support this claim.
Basketball-Reference.com reports the complete history of all NBA teams using win-loss record/percentage, offensive efficiency rating, defensive efficiency rating, and the SRS. When you rank the Spurs' seasons by these measures, the only one that appears to correlate well with their winning the title is the SRS, which is based on the average point differential and strength of schedule.
So far, the Spurs' SRS for this 2012-13 season is 9.12 (which equals points above average differential, with the league average differential rescaled to equal zero). This is the highest rating on this measure in Spurs history! Their next highest SRS rating is 8.35, the rating for their 2006-07 championship season. The other championship-season SRS ratings were 7.84 (2004-05), 7.12 (1998-99), and 5.65 (2002-03). Other notable seasons were when they lost the Western Conference Finals: SRS = 7.92 in 2002-03, 3rd highest in Spurs history; and last season, 2011-12, when SRS = 7.28, 6th highest in Spurs history.
Their winning percentage to date is .750. While there is a lot of season left to be played, and lots can happen to effect their chances, the Spurs have won more than 75% of their games 4 times without winning the championship, so while it is not the best predictor, it remains a decent one. Their percentages during title seasons range from .707 (2007 title) to .740 (1999 title).
The idea that the SRS is a good predictor of NBA championship outcomes is supported by Hollinger's rankings and playoff odds, which are heavily driven by the point differential in last 10 games. Today (1/7/2013), Hollinger predicts that the Spurs have the best odds to win the NBA title with a 32.7% chance and a 13.2 point differential in last 10 games. Amazingly, the Clippers are next at 20.6% and 8.8 point differential, followed by OKC's Thunder with a 18.2% chance and 8.3 point differntial. In the East, the Miami Heat have a 7.7% chance and 5.4 point differntial, and the Knicks have a 6.2% chance and 1.5 point differential.
Like Coach Pop, I subscribe to the "defense wins championships" mentality. For the Spurs, the evidence in support of this is strong, but the SRS captures both offensive and defensive efficiency. The more points scored per 100 possessions (offensive efficiency) and less points allowed (defensive efficiency) are captured well in a point differential statistic, and this would be true regardless of how much or little is being scored across the league overall.
The Spurs best defensive season was 2003-04 (allowed 94.1 points per 100 possessions), but they lost in the semi-finals that year. The 1999 championship season was their 2nd best defensive year, allowing only 95 points per 100 possessions. But we all know that scoring is higher across the league, and the Spurs rely on it much more these days. Still, the Spurs are currently 5th best in NBA defensive efficiency, allowing only 98.5 points per 100 possessions. This ranks as the Spurs' 4th best defense ever, so far; not bad for the 5th best offensive team in the league (scoring 107.3 per 100 possessions)! Only the Spurs and Clippers are among the NBA's top 5 in both offensive and defensive efficiency.
The Spurs are on the right track. Keep key players healthy, keep up scoring rate and improving defensive rotations, and the Spurs are primed for a championship run. Go Spurs Go!