Everyone is now trying to copy the Celtics’ love of 3-point shots

It hasn’t exactly been very effective, though, as the Bulls enter this two-game series with the Celtics 12-15 and ninth in the Eastern Conference. The problem in Chicago is that Billy Donovan’s defense is 29th in points allowed and 27th in opponent passing percentage.

But the Bulls’ organizational desire to shoot more 3-pointers is directly tied to the success the Celtics have enjoyed as a dominant 3-point offense. They lead the league with 51.1 attempts per game, 20 more than the least attempted team, the Denver Nuggets.

The NBA has become a copycat league. Teams no longer play according to their own style. They acquire players and build plans around the most popular and effective style, and that takes more threes than twos.

President of basketball operations Brad Stevens has spent years building a roster of versatile shooters and wings who can defend. This is the current NBA model.

As December 15th passes and 90 percent of the league is eligible to be traded, active teams are looking for these types of wings. They need shooters. They needed 3-D players. They need big players who can shoot.

What makes the Celtics so difficult to defend is that they typically put five shooters on the floor, meaning defenders are potentially at risk of allowing an open 3-point shot if they go to Jayson Tatum or Jaylen Brown. Having shooters on the floor completely opens the floor and keeps defenders away from the paint and away from the basket.

Also, many teams who increase their 3-point attempts have not yet mastered the other aspects essential to winning.

Celtics coach Joe Mazzulla is fully aware that opposing teams adopt elements of his style and philosophy. He was also ready to counter with new wrinkles that could give the Celtics more separation.

“I think the thing is that every team is different, and we don’t look at it from a league perspective. We look at it like: OK, every game you have to know that we are a great team, but you have to know that every team is better than you at something,” Mazzulla said. “You have to understand how strong this team is compared to yours, and how to fight it and win.

“When we play Chicago, their 3-point rate is up. Their transition rate is up, so there are a few areas where they are better than us. But this changes for each opponent. I think the key is to be open-minded and understand what those keys are for that particular game. What does this team do well and how can you exploit that? And how could you focus on the things you do well and try to do them longer than the other team?

In the first meeting with the Bulls on November 29, the Celtics won, 138-129, as they were 23 of 54 from the 3-point line to 20 of 51 for the Bulls. The Celtics defense struggled that night, especially in the first half. But Mazzulla made the smart decision to replace Tatum with Bulls center Nikola Vucevic, who made four 3-pointers in 93 seconds late in the second quarter.

It was an old-fashioned shootout, and opposing teams figure they either have to outshoot the Celtics on three shots or, as Memphis did earlier this month, allow a struggling shooter (in this case, Jrue Holiday) all the attempts he desires and bet on lack.

This is what happened. The Celtics were minus-12 as Holiday attempted 26 shots in his 30 minutes in a 127-121 loss at TD Garden.

They were plus-6 in the other 18 minutes, despite Tatum making 6 of 21 and Jaylen Brown attempting 14 shots, his fourth-lowest total of the season.

Mazzulla knows the Celtics are going to see a myriad of game plans from opposing teams, and most of them will include equalizing their 3-point production. The Celtics also want to improve their weaknesses, like scoring in the paint and other aspects that will give them the definitive advantage regardless of the opponent.

“I think that’s part of long-term success, can you do what you do better and longer than the opponent,” Mazzulla said. “I think it’s relatively possible (to be good at everything). What are we, first and fourth or second and fourth (offensive and defensive team)? (It’s third offensively and eighth defensively.)

“I think you have to be a well-balanced team. I think a bigger key than that is to be open-minded, to understand that you may need to change. You can face a team better than you in two areas, and you have to find a way to combat that.

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Gary Washburn is a Globe columnist. He can be contacted at [email protected]. Follow him @GwashburnGlobe.