The Chicago Bulls’ math problem has been well-documented. They’ve been one of the lowest three-point volume teams in the league over the last two years, and are beaten by an average of 2.7 threes or 8.1 points per game from behind the arc.

A big piece of the puzzle is on the offensive end as the Bulls are tied for 22nd in the NBA in three-pointers attempted per game. But the bigger issue, at least of late, has been the threes allowed on the defensive end.

Even without Jaylen Brown, Jrue Holiday, and Kristaps Porzingis, the Boston Celtics, who beat the Bulls 124-113 on Saturday night, highlighted the issue. They shot 21-of-48 from deep against the Bulls, which is good even by their incredible standards.

“I mean, they’re 8-1 without Brown,” Coby White said. “It doesn’t really matter who plays for them, they all play very well together. They stick to their identity.”

Their identity is taking and making a ton of threes. And now the Bulls are 2-9 when they allow 20 made threes in a game this season.

“We were obviously, on drives, trying to be there to help each other,” Billy Donovan said. “But when the ball got sprayed out, a lot of times they would just get it off before we could get there.”

The Celtics attempt and make the most threes in the league and are second in percentage, just 0.2 percent behind the number one team.

Their 42.6 attempts per game are 3.2 attempts more than the second-closest team, which is the same as the difference between the second and 12th ranked teams in the NBA.

Meanwhile, the Bulls’ defense is built to give up threes. They allow the highest percentage of threes to their opponents in the entire NBA. They’re second in opponent corner three-point attempt frequency and above-the-break three-point attempt frequency.

Giving up a ton of high-quality looks to the best three-point shooting team is a recipe for disaster.

“One of the things that happened that led to threes was ball containment,” Donovan explained. “Obviously, when you’re the back line of defense like he is, sometimes the rotation piece, he’s out of position because he’s having to help.”

Allowing threes is only part of the battle. Teams shoot 37.2 percent from three against the Bulls, but shoot 41.8 percent from the corners (28th), which is widely considered one of the best sources of efficient offense in the NBA.

“We gave up too many open ones in the first half, and it was our lack of ability to control the ball,” Donovan said. “Prichard downhill, White downhill, and then I think some of them, quite honestly, came off offensive rebounds. Early in the game, we did not do a good enough job putting bodies on people.”

In order to reduce opponent three-point volume, the Bulls need to do a much better job of limiting dribble penetration. Drives force defenses to shift and help, which puts them in rotation on the back side. If they’re scrambling to rotate out to the perimeter, there’s a good chance the opponent is getting a good look at a three.

And then, they need to secure the rebound.

“I feel like our first shot defense has been good,” Coby White said. “It’s just, you know, the offensive rebounds, which lead to the kick-out threes and leads to wide-open threes and defensive breakdowns. So we just got to, like I said, just limit them to one shot.”

The Bulls allowed 12 offensive boards to the Celtics, which resulted in 23 second-chance points for Boston. The Bulls had just two.

In related news, Nikola Vucevic had just two rebounds.

These themes reared their head against the Celtics, but they have been trending the wrong way for quite some time. After performing at a top-five level last season on defense, the Bulls are just 19th this season. In the month of March, they’re 29th.

“Oh yeah,” Donovan said when asked if he can feel the team’s drop-off in defensive efficiency and execution.

“The two things that have hurt us have been the rebounding and also the fouling,” Donovan said. “Those would be the two things that have stood out that have really kind of driven (the team’s defensive rating) down. Our first shot defense has not been bad. It’s been pretty good. But it’s been the second-chance opportunities that have hurt us. And then also I think some of the fouling, the ability to go vertical, and not try to reach.”

Clearly, the Bulls have some stuff to work on as they enter the final 11-game stretch of the 2023-24 campaign.

Up next: Bulls have a chance to get back on trac against the Washington Wizards on Monday.