Welcome (back) to the era of NBA defense

The NBA’s offensive evolution commands most of the attention. But the past few years have shown defensive evolution may be the key to winning it all.

Most NBA championship contenders are great on both ends of the court, but for most of the 2010s, the NBA was primarily an offensively-driven league in which scoring took precedence over getting stops. Between 2011 and 2018, only five of the 16 teams that made the NBA Finals (Miami in 2011 and 2012, San Antonio in 2013 and 2014 and Golden State in 2015) ranked higher relative to the league in regular-season defensive efficiency than offensive efficiency, and all but those Spurs teams had top-six offensive ratings. Only 14 of the 40 Conference Finalists in that span were better on defense than on offense, and three more had equivalent rankings on both ends of the court.

The playoffs presented slightly more balance between offense and defense, yet there was still a strong correlation between offensive dominance and playoff success. One champion and one runner-up from 2011 to 2018 had a better playoff defense than playoff offense, while two champs and one runner-up had equivalent rankings. Five of the eight NBA champions during that period had the most efficient playoff offense the year they won the title, and five runner-ups ranked in the top three.

Even defense-first regular-season teams like the 2011 Mavericks and 2014 Spurs morphed into offensive juggernauts in the postseason. The playoffs provide a far smaller sample of data than the regular season, but the statistical profiles and roster construction of title contenders in that era suggest that elite teams had to be unstoppable offensively and merely good enough on defense to slow their opponents down.

But with defensive innovation and leaguewide rule changes now curbing the rise in scoring efficiency, it seems the pendulum has begun to swing in the other direction. As offenses become increasingly skilled, spread out and difficult to stop, the ability to actually slow them down becomes more important, so teams that can stifle great offenses tend to separate themselves from those who can’t.

Since 2019, three of the four NBA champions have finished with better defenses than offenses in the regular season (again, relative to the league), and no champion during that time has been better than third in playoff offense. (The 2021 Finals were the first since 2010 in which both teams ranked higher in postseason defensive rating than offensive rating.) Defensive versatility has become essential at the individual and team levels, and that end of the floor appears to have again become the primary indicator of a team’s playoff viability.

The Golden State Warriors changed NBA offenses AND defenses

Every dominant team of the 2010s had some sort of defining defensive characteristic, but the leaguewide shift back toward that end of the floor was accelerated — as many current NBA trends were — by the 2015 Warriors, who established the template for how modern defenses operate.

Golden State’s embrace of small-ball and switching screens caused the rest of the league to do the same, and those two tactics remain the modus operandi of most contenders in today’s game. In response to the rise of switching as a primary mode of pick-and-roll coverage, LeBron James’ Cavaliers began hunting mismatches by screening the opponent’s worst defender into the action and exploiting him one-on-one, which heightened the importance of hiding — or completely eliminating — weak links on defense.

The emphasis on well-rounded personnel created an environment in which the Raptors ascended to the NBA throne with one of the smartest, deepest and most adaptable defenses in history. By varying its schemes and improvising coverages in the playoffs, Toronto revealed the importance of not only individual defensive versatility but schematic versatility as well. The chameleonic frontcourt of James and Anthony Davis allowed the Lakers to use a similar blueprint the following season while the Bucks, having fully leaned into protecting the rim and trusting the math, finally broke through in 2021 by taking a slightly more versatile defensive approach.

The most recent NBA Finals pitted the league’s two best regular-season defenses — and two of the most adaptable defensive teams of the last decade — against one another, and it was the Warriors’ ability to grind Boston’s offense to a halt that ultimately delivered them a championship.

Every Conference Finalist in 2022 ranked eighth or better in regular-season defensive efficiency, and all four had the schematic flexibility to adapt their approaches to the different offenses they faced. Meanwhile, offensively-slanted teams like the Nets, Nuggets and Jazz have face-planted in recent years because of their inability to slow their opponents down. One weak link can break an entire scheme in a way it couldn’t a decade ago, and it seems that elite offenses who can’t defend are more vulnerable in the playoffs than elite defenses who struggle to score.

It’s hard to tell whether we’re at the beginning, middle or end of this defensive era. The ripple effects of this stylistic shift are just beginning to take shape across the NBA, and the league’s trajectory raises fascinating questions about team-building and individual player value at the highest levels of the sport.

Will organizations start passing on offensive creators in the draft in favor of rangier, more versatile defenders? Is a single, dominant offensive creator more valuable because he can overcome elite defenses? Or does that archetype become less valuable because those players tend to be poor defenders and one-man offenses tend to eventually stall out in the playoffs? Does a player like Rudy Gobert, who can elevate a team into elite defensive territory, become even more valuable?

Given the way offensive superstars like Trae Young, Donovan Mitchell, Nikola Jokic, James Harden, Ja Morant and Luka Doncic have been exposed on defense, are two-way offensive engines like Steph Curry and Joel Embiid even more valuable in the postseason than we’d previously thought? And how might our perception of those same problematic defenders change if and when the NBA’s stylistic landscape shifts back toward offense?

We won’t gain full clarity on these questions until the NBA’s next stylistic epoch begins, and winning at the highest levels of the sport will always require teams to excel on both ends of the floor. Yet for now, it appears that defensive titans like the Warriors, Celtics and Bucks will remain best-suited to survive the brutal and constantly shifting terrain of the playoffs — until they aren’t.

All data courtesy of Cleaning the Glass.