Why can’t the Chicago Bulls hold a lead? With 19 games left, that question will define the season. ‘It becomes draining.’

It took only four minutes into the second half Wednesday in Detroit for Chicago Bulls coach Billy Donovan to call a frustration timeout.

On paper, things seemed to be going well — the Bulls led the Pistons 78-61 and Zach LaVine already had 21 of his 41 points — but that didn’t reflect the reality on the court.

The Bulls had been assertive and combative throughout the first half, holding a double-digit lead into the locker room. But they entered the second half with a different energy — carefree, relaxed.

After the starting unit coughed up three turnovers in two minutes, Donovan had seen enough. He attempted to regroup his players, but the early timeout did nothing to reinvigorate their energy. The Pistons stormed back for a 21-point comeback in the fourth quarter.

This isn’t a new phenomenon for the Bulls — in fact, it has been a vicious cycle dominating the season. For Donovan, this constant inconsistency reached a breaking point of frustration Wednesday that couldn’t be pacified by escaping from Detroit with a win.

“You see this team in the first 24 minutes of the game that’s playing unbelievable, beautiful basketball,” Donovan said. “Then you see a team looking lethargic, uninspired. It’s amazing to me, to be quite honest.”

The Bulls have preached consistency since training camp, repeating the word like a mantra as they flail below.500 in the final quarter of the season. Despite this emphasis, they have played a only handful of complete games. And with 19 games left, it’s hard to see a path forward for the Bulls to correct this critical flaw.

Even the most veteran players have begun to feel a sense of dread in the pit of their stomachs when a lead begins to slip away.

“It becomes draining,” forward DeMar DeRozan said. “We’ve just got to show a sense of urgency coming out of halftime, especially when we have a lead and understand the other team’s not going to lay down and just let us win. They’re going to gonna come out swinging.”

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At first it was slow starts. Now the issue lies in the third quarter, when the Bulls typically squander whatever advantage they manage to build up. The second-half collapses are especially frustrating in games such as Wednesday, when the Bulls showcased their ability to compete for the opening two quarters.

“That first half, that was some of the best basketball we played all season,” guard Patrick Beverley said.

Even after the slump to start the second half, the Bulls managed to piece together a 21-point lead by the end of the third quarter. The problem was what came next.

The fourth quarter has been a harrowing frame all season. The Bulls are the third worst team in the league with an 11-21 record in clutch games — which end with a margin of five or fewer points in the final five minutes — and they often place themselves in those clutch situations by allowing an advantage to evaporate.

Even in Wednesday’s game, LaVine felt the Bulls failed to “sit down” the Pistons in the fourth quarter.

“We did what we were supposed to do,” LaVine said. “We had an 18-point lead. We just can’t give it up in the fourth.”

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So where does the blame lie? Ask Donovan, DeRozan and the rest of the roster and they’ll offer the same response: “It’s everyone.”

But if the Bulls still hope to course correct, it’s clear someone will have to lead the charge. Lack of sustained energy isn’t an issue of switching up a scheme or a starting rotation; it comes down to mentality and leadership.

If the Bulls want anything to improve as they battle for a spot in the play-in tournament, that change will start with the intangibles.

“It’s exhausting to keep talking about it,” DeRozan said. “We’ve got 19 games left. It’s on us from here on out to not be here again.”