And when they desperately needed a bucket in the final 40 seconds, they had nothing left. They inexcusably lost, 117-11, to the shorthanded Hawks after blowing a 15-point third-quarter lead. The Hawks were without All-Star guard Trae Young, yet the Celtics were outplayed, outhustled and outcoached by an inferior opponent.
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The Celtics’ chances of reaching the quarterfinals of the NBA Cup are now damaged, so much so they’ll probably have to win their final three games to have a chance at the quarterfinals, which includes a matchup against the undefeated Cavaliers.
And they finally paid for their defensive slippage, lack of rim protection and stretches of halfhearted play that’s plagued them over the past two weeks. Boston committed 20 turnovers, yielded 20 offensive rebounds and 38 Atlanta second-half paint points.
The Hawks used their size and physicality to exploit the Celtics’ softness in the middle. Rim protection and defense is becoming an issue. The duo of Clint Capela and Onyeka Okongwu were a combined 15-for-22 shooting with 10 offensive rebounds.
They bullied any Celtic brave enough to stand in their path or they cross-matched and simply shot over smaller players.
The Celtics may be off to a respectable 9-3 start, but they are a team with issues to address. They have to be tougher. They have to rebound better and they have to punch first. Once again, they began this game sluggishly only to find a way to take control then allow their arrogance to coast once they owned a 15-point lead midway through the third quarter.
The Celtics thought the upstart Hawks were done, but Atlanta kept pushing, kept attacking the paint with no resistance and then grew more confident. The Celtics’ approach in the second half was borderline disrespectful toward their opponent.
After the game, Celtics coach Joe Mazzulla was brief but not exactly fuming. In his own peculiar way, he appeared to accept his team is far from a finished product, that they have glaring weaknesses and perhaps the embarrassing loss could serve as a reason for re-emphasis on the little things, especially toughness.
“They outplayed us at every facet of the game, beat us on all the [statistical] margins, they deserved to win the game,” Mazzulla said. “They played harder and they played more physical than we did. They got 20 offensive rebounds and forced us into 20 turnovers.”
The lesson here is the Celtics are beatable, especially when they’re not making threes at a 50 percent clip. Mazzulla loves to point out the “margins,” meaning shot attempts, 3-point attempts, assists and turnovers. The Hawks won because they attempted 25 more shots, thanks to those offensive rebounds and Celtics turnovers.
The Celtics are last in the NBA in points in the paint because they lack a dominant post presence and 56.5 percent of their shots are 3-pointers. But they’re 23rd in the NBA in paint points allowed; meaning teams are gashing their defense with twos on a nightly basis. And the Celtics have to make those twos more difficult. If not, they’re relying mostly on 3-point shooting to win.
“They got rebounds and layups on everybody, bigs, smalls, mediums” Mazzulla said. “They just outplayed us at both ends of the floor.”
When asked if the Celtics need to improve their rim protection, Mazzulla said: “Absolutely.”
The locker room was silent after the game. Jaylen Brown and Jayson Tatum know they both need to be better. Brown scored 37 points but missed three key free throws in the fourth quarter and committed six turnovers. Tatum still doesn’t appear 100 percent after spraining his ankle on that non-call Sunday in Milwaukee and then tweaked it again on a blocked shot of Larry Nance Jr. with 4:29 left.
He labored after that play and went without a field goal in the fourth quarter.
“It’s already tough to win in this league and when you give them second and third opportunities and you turn the ball over instead of getting a shot up, it makes it tougher on you,” Tatum said. “We just let go of the rope at the end of the third and gave them light and we just made it a ballgame.”
There will be no rest. The Celtics play again Wednesday against the same Brooklyn team that pushed them to overtime Friday by playing harder and wanting it more. The Celtics have to regain their toughness. They have to be more physical and imposing. They have to get back to diving for loose balls and matching their opponent’s intensity.
They have to chill on the arrogance and play with the same desire and passion they did throughout last season.
“Mentally, we were too careless,” Brown said. “This displayed that we weren’t in synch like we normally were, so we’ve got to be better at that. We didn’t fight how we normally do. This is part of the journey, but we’ve got some stuff to come. We’re not a perfect team. It’s a new season, a new journey and we’re looking forward to embracing those moments.”
Gary Washburn is a Globe columnist. He can be reached at [email protected]. Follow him @GwashburnGlobe.
