OKLAHOMA CITY — The Celtics talk of measuring progress in a different manner this season, because, according to the win-loss column, they’re not making much of it at all.
So, rookie coach Brad Stevens refers to the little things that his team does in defeats that represent small but perhaps significant signs of improvement.
That’s all he can do at this point, really.
“I thought our ball movement in the first half was really good,” he said late Sunday night at Chesapeake Energy Arena.
And that was it. He couldn’t squeeze any other positives from his team’s lifeless 119-96 loss to the Oklahoma City Thunder, who have the best record in the Western Conference (27-7).
It was the most points that the Celtics have given up all season.
It marked their fourth straight loss and their seventh in eight games.
Their ball movement was terrible in the second half, for what it’s worth.
And they’re now 13-21 with four more brutal games on their Western Conference road trip.
“Effort,” guard Avery Bradley said, pinpointing what he believed the Celtics lacked most against the Thunder.
But effort had been one of the Celtics’ calling cards, the one given even when they were overmatched: they were, at least, going to play hard — with effort. Why wasn’t it there?
“I honestly don’t even know,” Bradley said. “I just know that we won’t win games if we don’t bring effort every single game. We showed that tonight.”
The issues run deeper than that, according to Stevens.
“One of the things we’ve got to do as a group is, when things don’t go well, we need to collect ourselves quicker and make things go in our favor again,” Stevens said.
“When things are going well, they’re not bad. But when things don’t go well, we haven’t responded well lately.”
The Celtics had suffered close losses in recent weeks, but Sunday’s contest wasn’t much of one.
Boston trailed by 23 and the fourth quarter amounted to garbage time, with Kevin Durant (21 points, 8 assists, 7 rebounds) sitting out the final stanza, enjoying the view from the bench.
The Celtics were without reserve guard Courtney Lee, who didn’t play after the Celtics had reached an agreement to send him to Memphis for guard Jerryd Bayless, league sources told the Globe.
The deal is expected to become official Monday. But the Celtics couldn’t blame their performance on Lee’s absence.
Defense, they said, was the culprit after the Thunder, who were playing on the second night of a back-to-back after beating the Timberwolves in Minnesota Saturday, shot 52 percent from the floor, scored a whopping 50 points in the paint, and sank 24 of its 31 free throws.
“We didn’t help each other on defense very often,” Stevens said.
The players agreed, even though the Celtics had, entering the game, played well together on defense, often connected as one.
They just took the night off against the Thunder.
“They were scoring at will,” Jared Sullinger said.
The Celtics trailed by 10 at halftime — not an insurmountable deficit, but the talent-laden Thunder then went on a back-breaking 10-0 run in the third quarter that gave them an 83-62 lead.
Jeff Green felt like the Celtics didn’t respond well to that run, and that their poor response crippled their defense.
“We became a little bit attached to our man and it allowed them to get easy layups,” said Green, who scored 19 points.
In other words, the Celtics became selfish, a sin that, considering the makeup of this team, led to their being routed.
“Forget about offense; we’ve got to win games defensively,” said Sullinger. “If we get [consecutive] stops, I think we could’ve been in this game as badly as we shot the basketball.”
The Celtics had four players score in double figures, with Bradley adding 19, Jordan Crawford 17 and Kris Humphries 14 off the bench.
But Brandon Bass missed all but one of his shots and Sullinger missed eight of his 11 shots. And when the Thunder exerted a little of their firepower, the Celtics had nothing that could come close to matching it.
Yet, as Sullinger said, the Celtics’ struggles came mostly on defense.
Boston College product Reggie Jackson scored a career-high 27 points for the Thunder, including scoring 11 in the first quarter. Forward Serge Ibaka didn’t break a sweat as he poured in 17 points and 11 rebounds.
Former Celtics big man Kendrick Perkins even scored in double figures, adding a season-high 12 points.
“We weren’t helping each other on the floor,” Bradley said. “We weren’t talking.”
He added, “Defense wins games. And if we don’t play defense, we don’t win. Simple as that.”
With Lee gone, Green said, “It just calls for other guys to step up, gives other people an opportunity to showcase what they can do. We’ve just got to move on. We can’t dwell too much on it.”
But before Lee left, he wished his teammates good luck.
They’ll need it.Baxter Holmes can be reached at email@example.com. Follow him on Twitter @BaxterHolmes.