The Thunder’s defense makes them a legit contender

Heading into their New Year’s Eve game against the Dallas Mavericks, the Oklahoma City Thunder sit in third place in the Western Conference with a record of 22-13. They’ve actually been a bit unlucky to end up in that position, as the plus-6.1 points per game point differential paints them as a team that should actually be two wins better than they are. If their record matched their scoring margin, they’d be in first place, a half-game ahead of the Denver Nuggets. The Thunder have the NBA’s third-best point differential both overall and per 100 possessions, indicating that they’re a force to be reckoned with this season.

The Thunder being in this position is perhaps not all that surprising — OKC has two of the 10-15 best players in the league in Russell Westbrook and Paul George — but at least part of how they’ve gotten here is somewhat of a surprise. Oklahoma City once again has one of the best defenses in basketball, as they head into their final game of the calendar year with a defensive rating that is just 0.1 points per 100 possessions behind that of the Indiana Pacers for the best mark in the league, per NBA.com. And the Thunder have been working all season without the services of their best defender, Andre Roberson, whose effect on the team’s defense has been dramatic during his time as a regular rotation player.

In our season preview series looking at 10 of the most interesting players in the NBA for the 2018-19 campaign, we shone a spotlight on Roberson’s importance to the Thunder defense.

READ MORE: Deandre Ayton is just getting started

"Roberson defended the opposing team’s leader in usage rate on 25 percent of his defensive possessions, by far the highest rate on the team, per an analysis of Second Spectrum matchup data conducted by Krishna Narsu and myself. He also defended the opposing team’s leader in Offensive Real Plus-Minus on nearly a quarter of his defensive possessions (24.67 percent), again the highest rate on the team by a long shot. The next-closest player on the team was George at 17.66 percent, and many of those possessions came during the second half of the season when Roberson was already out.His ability to guard across multiple positions was also incredibly valuable. Roberson’s combination of size (6-foot-7, 210 pounds), length (6-foot-11 wingspan), and agility allowed him to seamlessly slide across the perimeter and defend primary ball-handlers, high-usage scorers, and off-ball marksmen alike. And because of his height and bulk, he could even shift onto the occasional big man and not get punished on the block.It should come as no surprise that, throughout his career as a regular rotation player, Oklahoma City’s defense has been consistently better with Roberson on the floor. Last season was no exception, but the difference between Roberson being on and off the floor was more stark than ever before. The Thunder defended like the best unit in the league with Roberson in the game and like a bottom-10 defense when he was on the bench."

Roberson has not stepped on the floor at all this season thanks to multiple setbacks in his rehabilitation from a ruptured patellar tendon, and still, the Thunder have assembled an elite point-prevention unit. They did not really add any significant game-changing defenders during the offseason. Their major acquisitions were Dennis Schroder and Nerlens Noel, and while Noel had previously shown that he has the ability to make a major difference on defense, he has played less than 30 percent of Oklahoma City’s minutes this season so it’s tough to credit him for much of the team’s ability to defend at an elite level even without Roberson.

Instead, the improvement has been a holistic one, with everyone chipping in to make up for Roberson’s absence, and with the Thunder replacing minutes that used to go to Carmelo Anthony and Raymond Felton with more minutes for Jerami Grant and Terrance Ferguson, and adding Schroder. The following chart shows the percentage of Oklahoma City’s minutes played by their rotation players from the past two seasons. The chart is color-coded so that the holdover players who are playing a greater percentage of the team’s minutes this year are shaded in green, the holders playing a lower percentage of the team’s minutes are shaded in red, and the players who were only on the team for one of the past two seasons are shaded in yellow.

The Thunder essentially divvied up Anthony’s minutes between Grant, Ferguson, and Alex Abrines, shifted the Josh Heustis and Corey Brewer minutes to Nerlens Noel and Hamidou Diallo, and both cut Raymond Felton’s playing time drastically and used Schroder to fill in for both Roberson’s typical floor-time and when Westbrook missed games due to injury. Add in a bump for Steven Adams and a drop for Patrick Patterson, and voila, you have very little defensive drop-off even with one of the best defenders on the team sitting on the sideline for the entire year.

Of course, it’s not just as simple as playing different guys. The guys you do play have to execute the scheme. And these guys are doing that incredibly well. What the Thunder want to do more than anything else is cut off access to the basket, and this team has done a better job of that than almost any other team in the league.

The average team drives from the perimeter to the rim 42.6 times per game, per Second Spectrum data on NBA.com. The Thunder, despite playing the fourth-fastest pace in the NBA, allow just 39.0 drives per game, per the same data set. When opponents do break through and get to the rim, the Thunder have done an excellent job challenging the attempts there, allowing a conversion rate south of 61 percent on at-rim attempts, the seventh-best mark in the NBA. Having Adams or Grant or Noel on the floor at almost all times tends to help there.

It also helps that the players providing them help on defense have been able to do much more than that this season. Grant, Abrines, and Ferguson, for example, have been far more effective offensively than Anthony was a year ago. The same is true of Schroder as opposed to Felton and of Noel and Diallo compared to Roberson, Heustis, and Brewer.

Oklahoma City’s offense has not been as effective this season (107.9 points per 100 possessions compared to 109.9 a year ago) but that’s largely because Westbrook can’t seem to hit a shot from anywhere. The drop-off in his true shooting mark from 0.524 to 0.478 explains a ton of the team’s overall offensive backslide. That drop-off is concerning over the long-term, but in the here and now, the Thunder have to be happy with what they’re getting out of the so-called Other Guys on the team — especially considering how well George and Adams have also played. It seems incredibly likely that Westbrook will play better over the balance of the season than he has so far, and if the supporting players can maintain their current level of contribution, that will make the Thunder an even more dangerous team than they appear to be right now.