Why NBA teams are desperate enough to use zone defenseson September 25, 2020 at 1:16 pm

THE LOS ANGELES Lakers entered the fourth quarter of Game 3 of the Western Conference finals trailing the Denver Nuggets by 18 points when Lakers coach Frank Vogel called for a zone defense — a strategic move NBA coaches once considered a last resort, but one that is becoming increasingly common this postseason.

The Lakers used their zone to rack up five steals in less than three minutes, cutting the lead down to as little as three points. And while the Nuggets recovered to win the game, the defensive switch nearly led to the second-biggest comeback of LeBron James‘ lengthy playoff career.

“As a coach, when your team gets down and you’re looking for something to try to give your team a spark, you try to change the game,” Vogel said. “Sometimes it’s a lineup. Sometimes it’s a coverage. Sometimes it’s zone defense, throwing it out there, just to break their rhythm a little bit.

“It doesn’t always work. It did tonight.”

In the ongoing battle between NBA offenses and defenses, offenses have dominated recently. The past two seasons have produced the most efficient offense on record behind ever-growing numbers of 3-point shots.

“I think that the offense changed drastically, and the defense stayed pretty much the same for a while,” Toronto Raptors coach Nick Nurse said, “and now I think the defense is starting to have to adjust to such a different and drastic style of offensive play.”

The heavy use of zones has been a key adjustment this postseason. And now the zone defense, once disdained, has the potential to reshape this year’s NBA Finals.

AS RECENTLY AS two seasons ago, the NBA zone defense — which has been allowed since 2001-02, when the league removed the “illegal defense” rule preventing its use — had all but gone extinct.

After peaking at 3% usage during the 2009-10 season, zone was used for just 638 plays in 2017-18, 0.2% of all possessions, according to Synergy Sports data. That was the culmination of six seasons of decline after zone defenses were more common in the NBA from 2009 through 2012, highlighted by the Dallas Mavericks‘ zone helping them upset the heavily favored Big Three Miami Heat in the 2011 NBA Finals.

Seven years later, Miami played a key role in bringing the zone back in vogue.

On Dec. 20, 2018, the Heat used a zone defense to slow down reigning MVP James Harden in a nationally televised win over the Houston Rockets. Harden, who was amid a historic run of 32 consecutive games of scoring at least 30 points, went just 7-for-23 from the field against the unorthodox defense.

Though Heat coach Erik Spoelstra dismissed the notion that there was any grand strategy behind turning to a zone a handful of games earlier — “We did it because our man [defense] wasn’t working,” he said — other coaches took notice of how much zone Miami was playing. The Heat used zone on more plays during the 2019-20 regular season, 802, than all 30 NBA teams combined in either 2016-17 or 2017-18. League-wide zone usage was up to 2.2% this season, its highest level since the lockout-shortened 2011-12 season.

While Miami didn’t need to use its zone to beat either the Indiana Pacers or Milwaukee Bucks, it has been a key factor in the Heat’s building a 3-1 series lead in the Eastern Conference finals heading into Friday’s Game 5 against the Boston Celtics (8:30 p.m. ET on ESPN).

Other coaches have taken notice. “One of the best things you can do is learn from real good coaches,” Utah Jazz coach Quin Snyder said. “And Erik is a terrific coach, so it calls your attention to it, and then you have to figure out: Is this applicable to our team in some way?”

One big reason coaches have traditionally shunned the zone is that NBA players can shoot right over the top of it, but modern NBA zone defense is no longer so vulnerable to outside shooting.

“Teams have tinkered with zone rules and tinkered around the three-second rule for the middle man, so it’s not your typical college 2-3 or 3-2 zone anymore,” said Detroit Pistons coach Dwane Casey, who was the architect of the Mavs’ 2011 defense.

“The way teams have bastardized the zone so much and tinkered with the zone, it’s really a glorified switch.”

This helps explain why the Heat’s zone was effective against Harden. Modern offensive superstars such as Harden all but demand that man-to-man defenses switch pick-and-rolls to keep up, which puts their defenders in uncomfortable positions — guards defending post-ups and big men defending one-on-one on the perimeter. In a zone, those defenders stay where their coach wants them.

Spoelstra has also changed where those players are by putting two athletic forwards on the perimeter in the Heat’s 2-3 zones, with the team’s smaller guards playing on the wings in the back line. That has made Miami’s zone defense more difficult for Boston to attack.

Snyder borrowed that innovation when Utah implemented a zone defense at midseason.

“Having more length at the top, that player has an opportunity to impact the offense two different ways,” Snyder explained. “From the corner, there’s one pass, essentially, one direction that you can go. From the top, a lot of times there’s two different directions that someone can pass.”

Despite their evolution, zones remain most vulnerable beyond the arc. So, their rise also required the NBA’s shot math to change.

THE DECLINE IN zone defense over the past decade coincided with the NBA’s love affair with the 3-pointer. But now, even with 3-pointers being attempted at record rates, zone is back on the rise.

“It’s such an interesting contradiction,” Washington Wizards coach Scott Brooks said. “We are shooting 3s more than ever, so why would you play a zone?”

When the Mavericks used zone in the 2011 NBA Finals with Casey as their defensive coordinator, they were exposing a Miami weakness. At that point, before adding Shane Battier and unleashing Chris Bosh as a 3-point shooter, the Heat had a shortage of shooting.

Now, every team looks to have as much shooting on the floor as possible. Yet, there’s a paradox to all these 3-pointers: In a counterintuitive twist, they’ve made controlling the area around the basket more important for opposition defenses.

There are two factors at play. First, five-out lineups in which every player on the court can shoot 3s have made it hard for defenses to cover enough ground to load up the paint against players driving from the perimeter and also get out to shooters.

“I think it’s either-or,” said Casey, whose perspective is borne out by the data. “You’re going to do one or the other. It’s hard to do both.”

Second, shots at the rim are simply more valuable. The average attempt in the restricted area was worth 1.27 points this season, as compared to 1.17 points for the average 3-point attempt from the corners and 1.05 points for 3-pointers taken from elsewhere on the court.

Because of that math, job No. 1 for a modern NBA defense is preventing opponents from getting to the rim, even more than preventing 3-pointers.

Among the NBA’s top 10 defenses in 2019-20, just one team (the Philadelphia 76ers) ranked in the top eight in preventing 3-pointers. Conversely, four of the top 10 (including Milwaukee and Toronto) were among the eight teams that allowed the most 3-point attempts.

However, six of this year’s top 10 defenses were in the top eight in preventing shots in the restricted area around the basket, per analysis of data from NBA Advanced Stats, and none in the bottom eight.

It’s here where the zone shines. Per Second Spectrum tracking, teams shot 3s far more frequently against zones (53% of their shot attempts, as compared to 38% of shot attempts against man-to-man defense). But zone defenses dramatically reduced shots in the restricted area, from 26% of attempts against man-to-man to just 16% against zone.

The increased emphasis on protecting the rim, and the zone’s effectiveness in doing so, has led three of the four teams in the conference finals to use zone this round. Only the Denver Nuggets, who are down 3-1 in the West finals, have yet to break it out.

UNLIKE IN COLLEGE basketball, where legendary coaches such as Syracuse‘s Jim Boeheim and retired longtime Temple coach John Chaney built their defenses around exclusive use of 2-3 zones, NBA teams have found it more effective as a counterpunch. Overall, Second Spectrum tracking shows zone defenses giving up slightly more points per possession (1.12) than man-to-man defenses (1.11).

“It’s a different look,” Vogel said. “Most zones in the NBA are not very good; there’s a lot of holes in them and can be easily exploited. It doesn’t always happen, but that’s why most of the league does not play zone for long stretches.”

Still, as Brooks notes, zones have value by taking offenses out of what they typically want to do.

“When you [face] a man-to-man defense, you can run a pattern,” Brooks said. “You know that if they guard it this way, OK this will be open, and, if they guard it this way, [then] this will be open. So you have your check points as a player and as a coach.

“But in a zone, it’s a little bit of organized chaos. You have gray areas. … You have some concepts, but you really have to be free-flowing. You really have to have a really stronger-IQ basketball team to be able to attack it consistently.”

No coach has made better use of zones to mix things up than Nurse, recently voted Coach of the Year. During last year’s NBA Finals against an injury-depleted Golden State Warriors team, Nurse went to a zone defense typically seen in high school — a box-and-one — to thwart Warriors star Stephen Curry. He went back to it again during this year’s Eastern Conference semifinals against Boston to try to slow down Kemba Walker after he tore apart Toronto’s defense early in the series.

“I’ve coached in a lot of playoff games now, a lot of playoff series and a lot of NCAA tournament games,” Celtics coach Brad Stevens said after Boston’s Game 7 victory. “I’d say we saw more defenses and more stuff … right when something worked, the next play it didn’t work anymore. That’s a credit to them.”

After outlasting the Raptors, the Celtics have struggled against Miami’s 2-3 zone in the conference finals. They’ve averaged just 1.04 points per possession on the 113 possessions marked by Second Spectrum data as against zone, down from 1.19 points per possession against man-to-man, while shooting 29% from 3-point range. In a series in which the Heat’s three wins have come by a combined 11 points, those possessions loom large.

Between players getting more and more creative with the ball in their hands, an influx of quality shooters at every position on the court, and rules being created and enforced to aid offense, defenses are left in a nearly impossible spot. The goal isn’t to take away everything from an offense, but to keep them from going to what it is they want to do most.

“It’s going to be hard for defense to trump offense like it used to in the late ’90s,” former Philadelphia 76ers coach Brett Brown said earlier this year.

Still, that won’t stop coaches from trying.

“The game has changed,” Brooks said. “I think zone defense is going to be taking place more and there’s going to be more creativity, and someone is going to come up with something that is totally different than the last guy.”

Read More