NBA defense is a most futile effort. Maximized by spacing, enhanced by analytics and bolstered by rule changes, offensive talent in today's league is almost too potent to stop. Even with a perfect game plan and seamless execution, you can give up 125 points.

As offenses homogenize, players become more adept with their preordained reads. Step back when the defense goes under screens; attack when it goes over. Pull up on drop coverage or play four-on-three to beat a trap. These reads are seared into the brain of every smart lead initiator. There is little improvisation—it's muscle memory.

Extreme measures are required to force the offense to think. An extra split-second can delay or even disrupt the entire orchestra. The challenge for the suits on the sideline is to figure out how to make that happen.

Over the past two seasons, zone defense has become that in vogue flow-stopper. Zone is far from the predominant defensive tactic, but it is quickly catching on as a mainstream tool. What used to be stigmatized is seen as "a natural rhythm changer," according to Mavericks head coach Rick Carlisle.

There were 437 zone possessions in the bubble alone, more than half the 718 possessions played in 2017-18, according to Synergy Sports data. Zone defense boomed in 2018-19 when that number ballooned to 3,824, and by the end of the 2020 regular season (bubble included), the total number was 5,361. 

Pistons head coach Dwane Casey calls zone "a glorified switch," which, if done well, can be like a defensive death lineup. This means keeping it in your back pocket—not necessarily for use at the end of games but sprinkled intentionally throughout a 48-minute period to throw off the offense's natural rhythm. 

"We're seeing a lot more of it. I think it's good in certain situations: short clock, out of timeout or to disrupt rhythm," Knicks coach Tom Thibodeau explained to B/R. 

Coaches draw up plays for these short-clock and after-timeout situations, so using a zone can help blow up what would normally be a chance for a high-quality look. A chess match between coaches within the chess match.

While most teams use zone strategically, the Miami Heat are setting the curve. They go all-out. They'll pick you up full-court, throw a 6'9" forward at your guard and have some of the crispest rotations in the league. Using the zone nearly twice as much as the next-closest competitor, coach Erik Spoelstra employs it as a "changeup" to help prop up their defense. He just throws his off-speed stuff a little more often than most.

"We put our length up front, which a lot of teams don't do, so that's probably an adjustment most teams aren't used to," Heat forward Duncan Robinson told B/R. "We can get two pretty disruptive guys up front, just to kind of wreak havoc on the ball-handler and the passing lanes."

Each team has a different idea of how and when to zone. The Heat are aggressive—trying to get the ball-handler to give it up—and rely on their length to scramble back into place. The Toronto Raptors, second in the NBA in zone possessions, are similar in their approach.

"It's always difficult with different bodies out there," Raptors forward Stanley Johnson told B/R. "Bigger bodies and bigger arms make a zone more effective."

The Raptors proved their brazenness in the 2019 Finals. They will try anything. They've continued to thrive this season as out-of-the-box thinkers, but whether they are in full-court zone press, 1-2-2 or 2-3 zone, the fundamental tenets on which these defenses are built remain constant.

"We do usually force those guys to put it on the deck a little more and hit driving lanes," head coach Nick Nurse said. "We've got to use other people and bring some help, and sometimes that gets us into a lot of rotations, but we know that, and we are in rotations a lot. It's not maybe something you would build your philosophy on, wanting to be in rotations a lot, but we do that pretty well too."

The Raptors didn't start the zone trend—they just made it famous. Now, teams are experimenting with an array of looks, but the common threads remain consistent: smart players and good coaching. Teaching the discipline, emboldening their players with trust and galvanizing the effort necessary to make a zone successful is no easy task.

"You actually have to play harder than man," Carlisle said. "It requires more concentration because you're constantly bumping to different bodies, and then you have to deal with a diminishing shot clock and rebounding."

On the other side of the ball, varying schools of thought exist about how to attack a zone. The general idea is to move the ball from side to side until the defense breaks down. Then attack the free space.

"You probably want to distort the zone some ways initially to try to at least have some variance in how you attack so it's not the same every time," Utah Jazz coach Quin Snyder explained of beating a zone. "A lot of times, it can be something as simple as pick-and-roll and spacing."

Snyder, one of the league's craftiest tacticians, even acknowledged it can be as simple as just shooting.

"In the NBA, the players are so good, sometimes the best thing you can do is get a shot off and make it," Snyder said.

The zone experiment is only the latest example of the game of catch-up that is the NBA. One team strikes gold with an idea, and the rest of the league, like moths to a light, imitates the trend. 

"The league is constantly changing," Thibodeau said. "We've gone through a period of time where there's a lot more switching. A lot of that is because of the downsizing of the power forward position, so you're seeing the switching 2, 3, 4, now you're seeing it 1 through 4. And the flip side of that, because teams have seen so much switching, they have become very adept at attacking the switches."

The key is to find the balance of being able to get the desired outcome without allowing it to become just another easy read for the offense. It's not complicated to recognize. "Right away, you can tell by the guy's defensive stance," Lakers guard Rajon Rondo said. Failure will leave you with the rest of the pack, waiting for the next innovation to copy. 

To win in the NBA is to make bold decisions without fear of them blowing up in your face. Inside the playoff petri dish, there is more time to prepare, adjust and counter. This means more time for coaches to prepare and show off.

Timely, well-executed zones could be the wrench that unravels an opponent.

All stats are from Synergy Sports unless otherwise noted.

Follow Will on Twitter, @wontgottlieb.