Tonight Gregg Popovich will begin his ninth foray into the Western Conference Finals. He will do so with as the NBA’s reigning Coach of the Year. This season was the third time Popovich has won the award, tying him with Don Nelson and Pat Riley for the most all time. His reputation is mighty and backed up by a volume of statistics — ninth among all coaches in regular season wins, fourth in regular season win percentage, third in playoff wins, tenth in playoff win percentage, third in conference championships, fifth in NBA championships.
But other than his droll wit and often prickly exterior, Popovich’s legacy seems to lack a definable quality. Nelson was an offensive mad scientist. Phil Jackson taught the holy trinity of the Triangle Offense and mentored some of the largest personalities the league has ever seen. Red Auerbach is the mathematician behind the “whole is greater than the sum of its parts” and Jerry Sloan speaks only in the language of pick-and-rolls and flex cuts.
Other than his personality, Popovich is known mostly for the culture he’s helped establish in San Antonio, a culture that has helped maintain success throughout a shifting sand of roster changes, all swirling around the pillars of Tim Duncan, Tony Parker and Manu Ginobili. But in terms of on court play there is little to cling to in describing Popovich as a coach. He’s teams have been both offensive machines and defensive juggernauts. They’ve played fast and slow, inside and out. Without any definable quality to latch onto, is it possible that Popovich’s greatness comes from his ability to be everything and nothing, all at once?
A few weeks ago Nate Silver journeyed down the rabbit hole at 538, exploring Popovich’s record of dramatically exceeding expectations. While Silver didn’t arrive at a definitive explanation for this dominant relationship between Popovich and expectations he did theorize that it may have something to do with his ability to adapt:
“What you might say about Popovich is that he’s been uniquely able to stave off regression to the mean. He adopts tactics and strategies to suit his situation; he stays one step ahead of his opponents. Under Popovich, the Spurs have succeed as an old team and as a young team, and as a fast-paced team and a slow-paced team. There isn’t much gimmicky about Popovich.”
If his ability to create stylistic shapeshifting teams is his gift, than we should be able to measure his success on both sides of that coin and identify his movements between them.
Wins and Win%, are the bottom-line measures of success in professional sports but win-related metrics don’t capture anything of the stylistic impact of a coach or how those results were achieved. It is generally accepted that point differential offers a clearer picture of a team’s ability than their record. Net Rating, which is simple a team’s point differential pace-adjusted to an average of 100 possessions then is a more accurate tool for judging a team’s performance than their win-loss record. But while using Net Rating and it’s sub-components, Offensive Rating and Defensive Rating (points scored and allowed per 100 possessions, ORTG and DRTG) can give us a more complete picture of the kinds of teams a coach has assembled, they create some problems for historical comparison. The average marks of efficiency for ORTG and DRTG fluctuate greatly by era. This season the average level of efficiency was 106.5 points per 100 possessions. In the 2000-2001 season that mark was 103.0, stretch back another 10 years and it was 107.9. Go all the way back to 1973-1974 and it was 97.7. These drastic fluctuations make it difficult to use the raw numbers of ORTG and DRTG for coaching comparison.
However, earlier this season Andrew Lynch of Hardwood Paroxysm created an elegant solution:
“Simple subtraction would get you one number, but a more accurate representation of the distance from the middle of the pack would be a percentage. And that’s just as easily calculated; we simply take the raw individual team defensive rating, divide it by the league average for that specific year, and multiply the result by 100. The product is a defensive efficiency number that’s adjusted to the league average for the season in which the team played. It measures what percentage of the league average scoring a team allowed; the lower the number, the better.
The same can be done for offense, too, of course, except in that case, the higher the number, the better. In a nutshell, this is what I’m calling ORtg+ and DRtg+, shorthand for “league-average normalized offensive/defensive rating.”
Lynch created his numbers for the comparison of team performance but we’ll be using them here to look at the track records of coaching.
Going back to the 1973-1974 season, 51 individuals have completed at least seven full seasons as a head coach. Using Lynch’s numbers we can calculate the average ORTG+ and DRTG+ of the teams coached by each. Remember that these numbers reflect an average of how each coach’s teams have performed relative to the league average in each specific season.
This first graph shows the average ORTG+ for each of the coaches in our sample:
Within this sample, teams coached by Popovich have the ninth-highest ORTG+, at 101.9. That means that his teams, on average, have scored about 1.9 percent more points per 100 possessions than the league average in each season. The coaches above him — Phil Jackson, George Karl, Mike D’Antoni, Jerry Sloan, etc. — carry some of the weightiest offensive reputations in the history of the league.
This next graph shows the average DRTG+ for each of the coaches in our sample.
At the zenith, you’ll find Popovich whose teams have, on average, allowed 4.8 percent fewer points per 100 possessions than the league average in each season. Popovich edges out some of the most respected names in defensive coaching, including Pat Riley, Larry Brown, Scott Skiles and both Van Gundy brothers.
If we put those two numbers together we can get NetRtg+, which is the average per 100 possession scoring margin each coach’s teams have put up against the league average in each season.
By this mark Popovich’s teams have been the very best in our sample and by a significant enough margin that Jackson is really the only other coach who comes close.
While these Popovich looks incredibly effective by these average marks it is also the consistent performance of his teams that has been remarkable.
In every single one of his 17 seasons as a head coach, Popovich’s team has had a DRTG better than the league average. Only Jeff and Stan Van Gundy have matched that perfect record but they’ve only coached nine and seven seasons, respectively. Popovich’s offensive consistency again ranks among the very best and altogether in 82 percent of his seasons as a head coach his teams have posted offensive AND defensive efficiency marks better than the league average.
But we’ve already hypothesized that neither excellence or consistency, offensively or defensively, is the greatest of Popovich’s achievements. That, most masterful of tricks, is adaptability.
His tenure overlaps, almost perfectly, with the career of Tim Duncan and, subsequently, Tony Parker and Manu Ginobili. These three players have formed the core of the San Antonio Spurs for more than a decade and as their games have developed and age has taken it’s toll Popovich has had to change the way the team functions around them.
The graph below shows the Spurs ORTG+ and DRTG+ for each of the 17 full seasons Popovich has coached them. The trends in each are shown by the heavier black lines.
While the team’s DRTG has stayed below the league average every season, their effectiveness has slowly eroded over time. However, the team’s offensive efficiency has improved at a rate that is almost completely identical. That means the Spurs Net Rating, and overall high level of performance, has been maintained at almost the exact same level across Popovich’s entire tenure. The side of the court which has driven that success has simply and subtly shifted.
Two parallel trend lines are not the most visually impactful statement of excellence, but they capture the essence of Popovich’s achievements. As his key players aged and changed he has continually updated the way his team goes about its business on the court. Within that sea of change, success has been a timeless, un-eroded island.