It's the summer of 2010, and it looks like the San Antonio Spurs' dynasty era is winding down. Coming off of an uncharacteristically mortal-looking 50-32 regular season, San Antonio ousted the Mavericks in the first round of the playoffs but were subsequently swept aside by the Suns, a team whose number they've traditionally had in the postseason. Worse yet, shrewd acquisitions like drafting Manu Ginobili 57th overall and signing Bruce Bowen from the scrap heap have been replaced by head-scratching moves, such as giving Richard Jefferson a $40 million extension. Nothing great can last forever, and the Spurs seem to be intent on proving that, as their best days are fading further into the rearview mirror.
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That's what most analysts were saying three years ago -- and who could blame them? But fast-forward to today, and the Spurs are sitting atop the Western Conference standings once again, a place they've occupied the last three seasons. And if anything, they seem to be getting stronger as more time has passed since the seeming crossroads they faced in 2010. Rather than a sign of trouble to come, or even the new normal, their aberrant 50-win 2009-10 campaign looks more and more like merely a flukish down year from one of the league's best clubs.
However, there is some evidence that the San Antonio narrative -- which seemed to be building back in 2010 (namely, that the team's true quality has in fact declined from the peak of Tim Duncan's heyday) -- wasn't 100 percent off the mark. Casual observers might point to the Spurs' stunning first-round loss to Memphis in 2011 and their collapse from a 2-0 lead against Oklahoma City a year ago as evidence, but there's even stronger underlying support for this hypothesis if you use a technique to identify teams that have been playing above their heads due to "luck."
Ah, luck. Formerly a dirty four-letter word in sports, the recent rise of analytics has made it a major fulcrum of any sophisticated study of the game. Luck comes in different flavors, but the common thread is that it can't be repeated, inflating or diminishing a team's record in ways that belie its true quality.
The seminal work on the subject of team luck was conducted a decade ago by sabermetric researcher (and Sloan Conference panelist) Phil Birnbaum, who wondered whether a team like the Montreal Expos -- who unexpectedly won 74 of their first 114 games before the players' strike prematurely ended the 1994 baseball season -- were truly a great team, or just fortunate in a small sample. He looked at traditional factors like whether a team overperformed relative to their pythagorean record (run differential), but also an often-overlooked component of any team's success: whether all of their players happened to sync up their "career years" at the same time. And as it turned out, those Expos were lucky on all of those fronts; not only did they win more than Pythagoras predicted, but their hitters and pitchers had much better performances in 1994 than in the surrounding seasons. Because of this, Birnbaum estimated that Montreal was really only a 61-win team that got to 74 wins purely because of luck.
When we replicate his study for NBA basketball, we can search for luck in similar areas. Teams can get lucky by exceeding their pythagorean win expectation; they can be lucky in terms of players producing above what projections say their true talent levels are; and they can be lucky due to favorable scheduling. For instance, through Saturday's games, the 2012-13 Warriors have won 37 games, but they've been extremely lucky in close games, and have gotten better seasons than expected out of many key players (though they have faced a more difficult schedule than the typical team). A system like Birnbaum's would suggest that Golden State is really a 31-win team that has received six wins' worth of luck so far this season.
"Luckiest" teams in the NBA, 2012-13
Team Wins SOS Career Years Pythagoras Total True Wins
San Antonio Spurs 51 +3 +245 +16 +264 42
Los Angeles Clippers 45 -5 +327 -71 +251 37
Brooklyn Nets 38 +19 +81 +103 +203 31
Golden State Warriors 37 -41 +98 +131 +188 31
Memphis Grizzlies 44 -20 +139 +51 +171 38
That makes the Warriors the league's fourth-luckiest team this season (Brooklyn is third and the Clippers rank second), but even they haven't been as fortunate as the Spurs, who rank first with an estimated 8.8 more wins than they deserve due to luck. Some of that has been under the auspices of schedule strength and Pythagoras, but mainly it's because of career years -- they've gotten unexpectedly great seasons from Tony Parker (adding 3.4 more wins than expected), Duncan (2.8 more wins), Boris Diaw (2.4 more wins) and Tiago Splitter (1.9 more wins), to name a few. Further, 8.2 of San Antonio's excess wins are due to players performing at a higher level than could have been foreseen based on their ages and established levels of play.
San Antonio Spurs player performance, 2012-13
Player Age MP Net Pts Projected Diff (Wins)
Tony Parker 30 1846 +205 +104 +3.4
Danny Green 25 1778 +65 +43 +0.7
Tim Duncan 36 1668 +143 +59 +2.8
Tiago Splitter 28 1631 +85 +27 +1.9
Boris Diaw 30 1491 +15 -58 +2.4
Kawhi Leonard 21 1392 +96 +101 -0.2
Manu Ginobili 35 1269 +90 +76 +0.5
Gary Neal 28 1217 -60 -29 -1.0
Stephen Jackson 34 928 -55 -37 -0.6
Matt Bonner 32 704 -3 +2 -0.2
DeJuan Blair 23 684 -2 +21 -0.8
Nando de Colo 25 677 -33 -4 -1.0
Patty Mills 24 580 -8 -2 -0.2
Cory Joseph 21 223 +4 -10 +0.5
James Anderson 23 94 -3 -5 +0.1
Aron Baynes 26 73 -5 -0 -0.1
The bad news for the Spurs is that such good fortune is fleeting. Computing this luck metric for every NBA team going back to the NBA-ABA merger in 1976, the correlation between luck in one season and the next is 0.03, meaning there's essentially zero carry-over from season to season. In other words, teams (like the Spurs) who have relied on luck to inflate their win totals should go into the following season expecting none of that over-performance to be retained going forward.
You might think one saving grace for San Antonio in this department is its coach, Gregg Popovich, known as one of the best the game has ever seen. Certainly we can attribute to Popovich some of the unexpected contributions of a player like Diaw, whose expectations were set relative to the overweight, undermotivated version we saw in Charlotte, not the semi-useful player he's been in San Antonio. But clear-cut coaching credit like that is rare. While the Spurs have defied luck in recent seasons (they've won 16.6 more games than they "should have," according to this luck metric, since the 2010-11 season), in more than 1,300 career games as an NBA coach, Popovich has only raised his teams' luck by about 1.2 wins per 82 games on average.
And the truth is that few coaches have shown any statistically significant impact on their teams' ability to produce positive numbers in the "luck" ledger. Rick Carlisle's teams have won 4.0 more games per season than they should; Pat Riley, Phil Jackson and Flip Saunders have added roughly an extra 3.5 wins per season; Chuck Daly added 3.1 and George Karl adds 2.3. Beyond those names, it's hard to find coaches who consistently make big impacts on their teams' luck factors. (And Popovich isn't even in that group -- his plus-1.2 mark isn't statistically significant from zero.)
Time and again, the Spurs have shown an ability to reinvent themselves and cobble together strong regular seasons in the face of an expected decline. But despite posting the best record in the West again this season, it needs to be recognized that a chunk of San Antonio's apparent success is built on unsustainable premises. Don't be surprised if that fact comes back to haunt the Spurs once more in the playoffs.
