Perhaps the most remarkable statistic of Tim Duncan's Hall of Fame career, which ended when he announced his retirement Monday morning, was this: Duncan never won Defensive Player of the Year.
In fact, despite making the All-Defensive First or Second Team 15 times -- far and away the most since the NBA introduced the All-Defensive teams in 1968-69 -- Duncan never even finished second in the voting for Defensive Player of the Year.
Nonetheless, as Duncan heads into retirement, it's worth pondering whether he's the best defender in NBA history.
Rebounder and shot-blocker
Duncan isn't the best shot-blocker in NBA history. (That would be Dikembe Mutombo, at least since the league started recording blocks in 1973-74, long after Bill Russell's retirement and the year after Wilt Chamberlain finished his career.) He isn't the best rebounder in NBA history. (That would probably be Dennis Rodman, but that's a debate for another day.)
However, what Duncan might be is the best combination of the two since the era of Chamberlain and Russell. In part because of how late the league started tracking blocks, Duncan is one of three players in the all-time top 10 in both blocked shots and rebounds, along with Kareem Abdul-Jabbar and Robert Parish. Those players got there more on longevity than sheer dominance.
Since 1973-74, according to Basketball-Reference.com, just two players rate ahead of Duncan in both defensive rebound percentage (26.5 percent of available defensive rebounds for Duncan) and block percentage (4.6 percent of opponents' 2-point attempts): Marcus Camby (27.9, 6.1) and DeAndre Jordan (27.2, 5.3), whose career is still ongoing.
There are others like Mutombo (26.2, 6.3) and Dwight Howard (29.1, 4.4) who rank narrowly behind Duncan in one category but are comfortably ahead of him in the other. They're in the discussion for best combo shot-blocker/rebounder in modern NBA history, too. But that discussion has to include Duncan in a prominent role.
Many good defensive seasons, no great ones
Turning to one-number defensive ratings provides the same conclusion as NBA awards voters: Duncan had many good defensive seasons (why he made the All-Defensive Team in 15 of his 19 seasons) but no truly great ones (why he never won Defensive Player of the Year).
Duncan's best season by defensive win shares on Basketball-Reference.com (7.2, in 2003-04) ranks 41st all-time. Hakeem Olajuwon had four better seasons, and five players in the blocked-shots era (Abdul-Jabbar, Patrick Ewing, Elvin Hayes, Howard and Ben Wallace) had two apiece.
However, when we change the criteria to seasons with at least five defensive win shares, Duncan's 11 are tied with Olajuwon and David Robinson for the most in the modern era. Only Bill Russell (12) has more such seasons.
Defensive win shares sum up box-score defensive stats (blocks, steals, defensive rebounds and fouls), adding a healthy dose of team performance. Those limited available metrics can't capture much of how a player can affect a game defensively. That's why I prefer ESPN's real plus-minus (RPM) as a defensive metric. Though RPM only dates back to 2000-01 because it requires play-by-play data, it offers a similar conclusion about Duncan since then.
The best Duncan season by defensive RPM (2002-03, when he rated 5.7 points per 100 possessions better than the average defender) ranks 16th in the last decade and a half, behind four Wallace seasons and a pair by contemporary Kevin Garnett. But of the top 100 individual seasons by defensive RPM, Duncan has an incredible 12 -- far better than Garnett (eight) for the most in that span. (A 13th Duncan season ranks just outside the top 100.)
Duncan's defensive longevity is remarkable. As the press release announcing his retirement noted, Duncan led the league in defensive RPM during the 2015-16 regular season at age 39. (Andrew Bogut subsequently surpassed him during the playoffs.) Nobody else has been so good defensively for so long.
Elite team defense
Of course, we can't talk about Duncan's defense without talking about how the Spurs defended as a team during his career. San Antonio had the league's best defensive rating in seven of Duncan's 19 seasons, including his final one, and ranked in the top three seven more times.
Obviously, Duncan can't claim all the credit for how well the Spurs defended during his career. That's also a testament to San Antonio's defensive scheme under head coach Gregg Popovich and a series of quality teammates, including Robinson, wing stopper Bruce Bowen and two-time Defensive Player of the Year Kawhi Leonard.
Still, as plus-minus data bears out, the Spurs consistently defended best with Duncan on the court, and their consistency defensively sets Duncan apart from nearly every defender in NBA history. Even dominant shot blockers like Mutombo and Olajuwon were occasionally part of average or even worse defenses.
Only one other player can truly match Duncan's success at the team level: Bill Russell. Complete defensive data isn't available for Russell's career, but from what we can tell, his Celtics teams won their 13 championships primarily on the strength of their defense.
Basketball-Reference.com's estimated defensive rating has Boston with the league's best defense 12 times in Russell's 13 seasons. They were second the other season. Obviously, that's a lot easier to do in a league with eight teams, which the NBA was at the start of Russell's career. But it's also worth noting Basketball-Reference.com estimates the Celtics were sixth out of eight teams in defensive rating the year before Russell's arrival, and they slipped to eighth (by then out of 14) the year after he retired.
Relative to league average, the Celtics have the two best estimated defensive ratings in NBA history (the 2003-04 Spurs rank third) and take five of the top nine spots, as Neil Paine noted on Five Thirty Eight this postseason. And while writing for Basketball-Reference in 2010, Paine found that the five players who played for the best defensive teams were all either Russell or his teammates. (Duncan and his teammates were in spots six through eight at that point.)
Defensive win shares come to the same conclusion. Duncan's 106 defensive win shares easily outdistance anyone else in the blocked-shots era -- the next-closest player, Abdul-Jabbar, is closer to eighth place than he is to Duncan -- but are nowhere near Russell's total of nearly 134. Given all the evidence, Duncan can claim to be the greatest modern defender, but when it comes to all of NBA history, he and everyone else are looking up at Russell.