CHICAGO -- If there was an easy way to explain the frustratingly mercurial nature of the Celtics, Marcus Smart would have done it.

But how does one properly characterize a team that has beaten the four clubs above it in the Eastern Conference standings and lost to three of the four with the worst records in the league?

"I don't even know what to say," Smart said quietly late Saturday night after a 126-116 loss to the now 16-44 Bulls. "I ain't got no words. I ain't got no words."

Seemingly numbed by the defeat -- and what such inconsistency may say about his team -- Smart played with a "Wheel of Fortune" app on his phone as he spoke.

And in a way, the app is apt. After 60 games, everything the Celtics want this season is still in play. They have 37 wins and the ability to rise to the bigger challenges. Kyrie Irving was putting on a good front when he said, "I still don't see anybody beating us in seven games," but the spectrum of postseason possibility is wide.

The Celtics could solve the puzzle. Or they could land on bankrupt.

If they were to buy a vowel, it could be an "e" with the hope of spelling "effort." But Smart had another "e" word in mind.

"Yeah, we're good. We're still in a good position," he said. "We've got a lot of basketball left. We lost here last year. We got blown out here last year (108-85 in December 2017), and in the end of the season we were still fighting for everything we wanted to fight for. We still were in the last game of the conference finals. So this is not the end of the world, but it is embarrassing. It's embarrassing. Just our effort is embarrassing. How we played is embarrassing."

Similarly, Brad Stevens wasn't happy with the performance, and he again chose to say it was he who had to improve. Three times he said he needed to do better. Asked for specific areas, the coach said, "I've just got to do everything. I have to make sure that we're playing better on offense. We can't let our transition slack like that. We've got to defend with more purpose and more intensity in the ball. We can't have those runs against us like happened in the second and third quarters."

While we cannot be certain precisely what Stevens is telling his troops behind closed doors, we're going to go out on a limb and assume he did mention a thing or two about hustling back on defense in transition and generally playing with more purpose and energy.

According to Smart, this is a player problem.

"It's all simple," he said. "It's just effort. Just effort. That's definitely it. It's plain and simple. Just effort.

"You know, we've got all the talent in the world, but, you know... I don't even know what to say. Like, really, I have no words."

It's hard to fathom how the Celts could go to the wire with the Bucks in Milwaukee Thursday, then allow both Zach LaVine and Lauri Markkanen to score their career highs when the Bulls were playing on the second night of a back-to-back. And with a Tuesday date with the Raptors in Toronto on tap, they cannot afford to let the Bulls performance linger.

"It's game to game," said Irving after scoring 37 points in 41 minutes. "We've beaten the tough teams in this league. We've proven we're capable of beating the tough teams in this league and playing well against them. So I'm not sure."

Jaylen Brown has a pretty good idea.

"Yeah, just playing with some more urgency," he said. "We've got to start building habits, and we let today get away from us. Chicago, give credit to them. They came out and played hard. They played like they wanted to win tonight, and we didn't play like we wanted to win, so we lost. We've just got to come out and play with energy that we know we can play with, no matter the opponent. It's not about who we're playing, it's about us."

As for whether the Celtics are playing with the type of energy needed to be what is expected of them, Brown said, "No, I think we've got to pick it up, and we know it. Everybody knows it. It's nothing that we can't fix. We've just got to come out and play with better energy. I think we played a good game against Milwaukee, a tough, hard-nosed game. But we came out and we didn't play with the same energy that we used against Milwaukee. So we've got to come out and be ready to play. We can't just click it on in the playoffs. So that's just a part of everybody just putting in that effort and that mindset, and we can do it."

The evidence is there to support his claim, but nights like Saturday do not engender confidence. Irving was asked why he doesn't believe the Celts' issues will drift into the postseason, and he now famously replied, "Because I'm here."

But all the Celtics have to show up -- on both ends of the floor -- when it's time to spin the playoff wheel of fortune. If not, their 2018-19 dreams will be in serious jeopardy.