Without Tim Duncan, the Spurs Are Missing Their Shield

Way back in 1996, the San Antonio Spurs started the season 3-15 while their best player, center David Robinson, sat out with an injury. At the end of that stretch and just before Robinson's first game back on the floor, a general manager named Gregg Popovich fired Bob Hill as the head coach and installed himself in Hill's place. Robinson returned for the Spurs' next game, but lasted only two weeks before suffering a season-ending injury. The Spurs slumped to a 20-62 record on the year, third worst in the NBA.

San Antonio lucked out and won the lottery that offseason, though, and the rest is literally NBA history, because the prize of the 1997 draft was Tim Duncan, the best power forward of all time (even though, despite his and Spurs fans' objections, he often played center) and the greatest Spur ever. During Duncan's 19-year NBA career, the Spurs won 1,072 games—155 more than the next closest team. They were consistently great for a great many reasons, but maybe the most important of them was that you could always count on the Duncan-Popovich Spurs to be somewhere between very good and elite on defense.

On Tuesday night, the Spurs will begin their first season without Duncan since the advent of Google. Needless to say, the task of keeping opponents from scoring baskets is about to become considerably more difficult.

During each of Duncan's 19 NBA seasons, the Spurs finished with a defensive efficiency that was better than league average. Their cumulative defensive rating during that time, per Basketball-Reference, was 2.9 points per 100 possessions better than the next closest team. That differential is almost exactly the same as the one that separates the runner-up (the Indiana Pacers) from the team with the 19th-best defense since 1997 (the Vancouver and then Memphis Grizzlies).

The Duncan–Pop Spurs finished inside the league's top three in defensive efficiency every season from 1997-98 until 2010-11, which wound up being the only season of Duncan's career where the Spurs finished outside the top ten. They finished first six times, second five times, third four times, and fifth once. They finished outside the top five all of three times—each season from 2009 to 2012—and all they did after that was rebound to finish third, third, second, and first during Duncan's final four NBA seasons.

Duncan himself was, of course, the lynchpin of all that, even over the last few years. Kawhi Leonard may have just won back-to-back Defensive Player of the Year awards, but ESPN's Defensive RPM still pegged Duncan as the team's most valuable defensive player during both of those seasons, and in 2013-14 as well. Timmy finished third, fifth, and second in the entire league during the three years ESPN has tracked the stat. Leonard was the tip of the spear, cutting the head off the opponent's best offensive threat; Duncan was the shield, protecting San Antonio should any opposing player break through the first line and try to stick them with a shot to the body.

Heading into the 2016-17 season, the Spurs won't exactly be bringing a knife to a gunfight on defense, but it's considerably more difficult to defend yourself when you don't have a shield. They're also old as the hills yet again, which doesn't necessarily help. They have a projected minutes-weighted age of 30, per ESPN's Kevin Pelton, which will make them among the two or three oldest teams in the league. (The projection came out before Danny Green got injured, which is expected to keep him out for a few weeks, but it's unlikely to drop: Green is 29; the player most likely soak up the majority of his minutes, Jonathan Simmons, is 27.) More experienced teams tend to be better on defense than their younger counterparts—for example, see last year's Spurs, with a minutes-weighted age of 30.3—but tip too far and you're asking for trouble.

They do still have Leonard, of course, as well as the tactical brilliance of Popovich on their side. But they've replaced Duncan—again, one of the league's best defenders—at center with the combination of Pau Gasol and David Lee. We'll charitably call Lee a minus defender and leave it at that. Actually… no, we won't. He's one of the worst defensive players of his or any era. It will be a minor miracle if Popovich can figure out a way to hide him.

Gasol still works well as a stationary rim deterrent (opponents shot 49.2 percent when he was the closest rim defender over the past three seasons), but he increasingly resembles a statue when tasked with guarding in space. Over the last three seasons, per privately provided SportVU data, Gasol has been targeted in 3,775 pick-and-roll plays. Those pick-and-rolls yielded an average of 1.04 team points per play, a figure that would rank in the league's bottom third or worse every year.

Couple the downgrade at center with a point-guard crop that is defensively uninspiring at best (Tony Parker's defense is nearly as statuesque as Pau's these days), and you have a recipe for some unsightly pick-and-roll defense. Considering the pick-and-roll is the foundation on which every non-Knicks offense in the league is built, that might be a bit of an issue.

How do the Spurs guard a Stephen Curry and Draymond Green screen-roll when the Golden State Warriors roll out the Death Star Lineup? What about Russell Westbrook and Steven Adams, or Chris Paul and DeAndre Jordan? Is Gasol or Lee stepping out far enough to contain any of those point guards? Does Popovich even want them to? If the Spurs change things up and put LaMarcus Aldridge on Green or Adams or Jordan, what do they do when those teams come back with screens set by Kevin Durant, Enes Kanter, or Blake Griffin?

Popovich will almost certainly have schematic answers to all these questions, or at least workarounds for them. The Spurs will help off of the right shooters and give up the right kind of shots and they'll rarely ever foul. They'll be in the right place at the right time more often than not, so long as their old-ass bodies allow. They'll move on a string as one unit, always. But it will be more difficult than it has been in the past.

Are the Spurs going to be a bad defensive team? Almost definitely not. It may not actually be possible for a team with Popovich at the controls and Leonard wreaking havoc on the wing to be bad on defense. But they may merely be good rather than great, which for the Spurs would be a pretty big change. Because of Popovich's two-way tactical brilliance and the pillar-like sturdiness of Kawhi and LaMarcus Aldridge, this may not actually affect the Spurs' record all that much, but by the time they get to the playoffs, it seems likely to prove their eventual undoing.

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