The Chicago Bulls are in a rut. That’s clear enough from their four-game losing streak in which they topped 100 points only once. But it also has been evident just from an eye test — players seem out of sync and out of sorts, relapsing to an isolation offense that fell away from the movement-heavy style that powered wins this season.

And now they face the gargantuan loss of leading scorer DeMar DeRozan, who did not travel to Indianapolis for Wednesday’s game against the Pacers because of a right thigh strain he has been playing through since December.

It’s unclear how long DeRozan’s absence will last. But whether he’s on the court or the sideline, the struggling Bulls are still facing a clear task — kick-start the offense that at one point seemed to keep them afloat.

Despite allowing a high rate of 3-pointers, the Bulls have remained in the top 10 in defensive rating (111.8) and jumped to the top five (105.3) during the losing streak. But their offensive rating has plummeted to 94.4 over those four losses — the worst in the league.

“We’re just getting stagnant. We’re turning the ball over at a high rate,” DeRozan said after Monday’s loss to the Orlando Magic. “Those two things are killing us. Teams get confidence when we do things like that. They pick it up, get more aggressive with us. That’s all on us.”

Coach Billy Donovan believes the sudden slump in the offense comes down to one common thread — decision-making. The Bulls are missing extra passes, balking at looks they should take and forcing up lower-percentage shots.

And those issues only compound later in games — the Bulls averaged the fewest fourth-quarter points (18.3) and assists (three) in the league during the skid. At the same time, they averaged 12.3 turnovers, handing their opponents 17.8 points per game.

Although the issues have been exacerbated during the losing streak, Donovan thinks it’s a reflection of seasonlong issues that have resulted in a plethora of missed opportunities — especially in transition, in which they average only 20.3 points despite forcing 14.7 turnovers per game.

“We’ve been botching fast breaks a lot this season,” Donovan said. “We’ve got to get better at taking care of the ball and finishing.”

Let’s get this part out of the way: Yes, the 3-point shooting has also been bad. It isn’t just the usual problem that the Bulls aren’t taking enough 3s — they averaged 3.7 more attempts during the skidthan their season average. But the Bulls are 26-for-125 (20.8%) from behind the arc in their last four games.

In their last two losses, the Bulls didn’t make a 3-pointer until the third quarter. Even though they aren’t a 3-point-dominant team, Donovan believes this directly affected the offense by forcing players to feel limited in their shot-making options.

“The deterioration of our decision-making was impacted by how poorly we shot the ball to start,” Donovan said. “It’s instinctive to say, ‘OK, let’s just get something to the basket.’ I don’t think we’ve been a team that’s lived by the 3 and died by the 3, but clearly when you’re not shooting the ball well, guys have been instinctively trying to go toward the basket.”

It’s not clear where the Bulls will find a spark. Even when he’s available, DeRozan is clearly hampered by his injury. Zach LaVine’s bounce has returned, but hero ball isn’t a solution for a dysfunctional offense. And the bench has one of the lowest offensive ratings (52.4) in the league — and that has plummeted to 48.4 over the last 15 games because of injuries to key players like such as Alex Caruso and Javonte Green.

But one thing is certain — with barely 21 games left in the season, time is running out for the Bulls to find answers.

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