The Twilight Zone: How Much Zone Defense Does The NBA Use?
And why hasn't it established a greater foothold in NBA defensive schemes?
Thanks to the miracle of tracking technology1, we are able to comb through public data to understand some things we could only guess at before. One of those things is the prevalence of zone defense (or lack thereof) in the NBA.
Despite some high-profile exceptions, the data shows that zone defense is quite rare in the NBA and hasn’t been particularly effective when deployed.
Common Types of Zone
Zone defense is when players are assigned to guard specific areas on the floor instead of specific opposing players. There are a vast variety of zones, but the most common you’ll hear about on broadcasts are the 2-3, the 3-2, and the box-and-one.
A 2-3 is easy enough to understand. You put two players (traditionally your guards, although that’s increasingly less common) at the top, two in the corner, and one under the hoop. Here’s an example from a Miami Heat game last season (although sharp-eyed readers may notice that the Heat’s guards, Herro and the since-departed Goran Dragic, are the ones standing near the corners):
A 3-2 zone is the inverse, with two guys roughly at the elbows, one up high, and two responsible for the paint and the corners:
A box-and-one is a hybrid. Four guys in a rough quadrilateral shape play zone, while one guy chases the other team’s best player no matter where he goes (usually deadeye shooters like Steph Curry who might otherwise abuse a zone). The picture at the top of this article is an example of the box-and-one the Raptors ran in the NBA Finals in 2019.
Why Zone Isn’t Common In The NBA
Zone is heavily used in youth basketball, and many teams (most famously Syracuse) run it as their primary defense even in college. However, the NBA had outlawed zone defense until 2001, and it hasn’t made huge inroads into the modern professional game.
There are a few reasons zone isn’t widespread:
The defensive three-second rule prevents teams from simply stationing their best rim protector right under the basket (a common strategy at every other level). Just like on offense, defenders can’t remain in the paint for more than three seconds at a time.
Most zones will give up certain spots on the floor that are vulnerable to shooters, a problem given the elite shotmaking of NBA players at almost all positions today. It’s a common belief that a team can shoot defenses out of a zone too easily.
Zone defense makes rebounding harder because it becomes trickier to find an offensive player to box out.
Because there are always soft spots in any zone, they can be picked apart by teams with quick decision-making and excellent passing.
Given these limitations, you might understand why many coaches are hesitant to employ large amounts of zone. The three-second rule, in particular, has defanged many standard zone defenses. In 2020, Pistons coach Dwane Casey pointed out, “The way teams have bastardized the zone so much and tinkered with the zone, it's really a glorified switch."
So why would an NBA team use zone? There are plenty of reasons why it can be situationally advantageous.
For many teams, it’s a desperation play if their man defense is getting lit up too easily. Some squads like it to combat an offense that might have a strong interior presence but poor outside shooting (zones can make it easier to dig in on a post behemoth). Some teams do it at random times to throw a different look at an offense in the hopes of confusing or stalling a team for a few possessions here or there.
The most common situation for zone in the NBA is immediately after a timeout (or before an out-of-bounds play), when the offensive team is likely to run a scripted play. Most NBA teams have traditionally set up their plays to work against man defenses, so many coaches employ zone to disrupt these plays.
NBA zone has been on the rise in the public consciousness since the Raptors famously went box-and-one on Steph Curry in the 2018-2019 NBA Finals. Anecdotally, I’ve noticed more announcers calling out when they see zone during television broadcasts over the last few years.
Greater awareness of the zone doesn’t mean that there actually is more zone. Synergy data shows something different. When I look at zone usage from 2019-2022 (and at 2011-2012, to establish a historical precedent), I find that zone usage in the NBA is very low and fairly consistent:
In general, zone is consistently used between 2% and 4% of the time in the NBA. An average team has roughly 100 possessions per game (and most, but not all, are halfcourt possessions), so that means the NBA uses zone…checking abacus…almost never!
Breaking it down by team does show some interesting philosophical differences. I apologize to mobile readers, who may have to squint a little:
Some of the more noteworthy teams:
The Raptors use all manner of funky zones, from box-and-ones and triangle-and-twos to inverted 2-3s in which the big men play up top and the guards play down below. It’s no surprise to see them among the league leaders each year; if anything, I’d have expected the number to be higher!
Milwaukee has also run a lot of zone this season as they try to maximize their defensive performance without many key players for long stretches, including former All-Defensive Team center Brook Lopez.
The Hornets have long been one of the worst defensive teams in the league, so it’s no surprise that they are using a relative ton of zone — 11.1% this year, down from 13.6% last year. They’ve never really had the personnel for a lockdown man defense, and zone is an easy crutch to try and stem the bleeding.
The Blazers have been the worst defense in the league for most of this season, and new coach Chauncey Billups has experimented heavily with zone in a break from predecessor Terry Stotts’ rigid defensive schemes.
The Heat are on the opposite side of the spectrum as a zone-heavy team that’s very good on defense. Miami has been a top-10 defense each of the last three years. The Heat’s rosters are typically dotted with many strong individual defenders and a few glaring weaknesses (*coughRobinsoncough*), so zone lets Miami hide their weak points (usually in the corners) while emphasizing their better defenders at the point of attack.
The Heat were at the vanguard of the trend of putting tall, athletic forwards at the top of the zone, typically where shorter guards play, to disrupt passing lanes and contest jump shooters, something teams ranging from Toronto to Utah have also done.
At the other end of the spectrum, Knicks coach Tom Thibodeau hates zone (his outdated defensive principles preclude the idea of anything less than MAXIMUM MAN ALL THE TIME).
The Nets, under coach Steve Nash, have also eschewed zone. This makes sense, as stars Kevin Durant and James Harden famously prefer to use switch-heavy man-to-man coverage, which can be less exhausting.
Zone defense does best when intelligent players can practice it rigorously. They need to know when to cede a moving ballhandler to a teammate, practice boxing out, and decide who is responsible for the overlapping areas of responsibility. This could be why teams with high roster turnover, like the Chicago Bulls, don’t run much zone, although I’m speculating here (and coach Billy Donovan has never employed much zone).
Overall, I was surprised to see that zone is not noticeably increasing. There is always the possibility that Spectrum is undercounting the number of zone possessions being run (many match-up and hybrid zones look a lot like traditional man defense, except with extra nuance). However, it’s clear that man-to-man is still the dominant defense of the day.
That could be because zone defense consistently gives up more points per possession than man defense:
With the first view, we see that the NBA, in general, fares worse with zone defense than with man defense. Zone defense consistently gives up about 0.05 points per possession more.
The second chart shows the difference in points per possession for each team. This chart can be a bit misleading thanks to small sample sizes. Some teams, like the Grizzlies, look like masters of the zone. But that’s a trap.
If you refer to the previous chart earlier in the article, you’ll notice the Grizzlies have run zone just 0.3% of halfcourt possessions, or 13 total possessions this season, so we can’t draw any conclusions from that. The Hornets, on the other hand, run a lot of zone and have some success with it compared to their man defense.
Take these findings with a grain of salt, as this isn’t a strict apples-to-apples2 comparison, and sample size is low-to-zero for some teams. However, it’s clear that zone isn’t a magic bullet for lousy defenses (or else we’d be seeing more of it).
With the increasing shooting and passing skill we see entering the league, it seems unlikely that the zone will ever amount to anything more than a gimmicky defense in the NBA.
IN CASE YOU MISSED IT:
All numbers are from Synergy Sports
There’s a clear selection bias issue here. Coaches usually use zone A) against opponents for whom they deem it advantageous, B) out of desperation/change of pace, or C) coming out of a timeout, when offenses often use a predetermined play. These are inherently different situations than your average man defensive possession, so comparing man PPP to zone PPP isn’t really fair.