Celtics Defense Slips and Effort Wanes Again in Thunder Loss

An ominous stat spread on Tuesday morning highlighting the seismic December shift in the eastern conference.

The Nets, who won 12 straight games since their loss to Boston, rode the second-best isolation defense in the league under Jacque Vaughn to pull within one win of tying the Celtics atop the east on Monday.

The Celtics, who fell to 9-8 over their last 17 games with a historic loss to the Thunder, ranked 25th in guarding isolations entering the game, allowing 1.02 points per 100 possessions, according to Synergy.

That played out during the 150-117 disaster in Oklahoma City on Tuesday. The most active driving team in the NBA attacked each Celtics defender across the board. Malcolm Brogdon and Jayson Tatum fell over each other guarding a Jalen Williams pick-and-roll drive, Al Horford struggled to guard on the perimeter and Marcus Smart got ejected to conclude another rough performance.

How the Celtics answered an inevitable shooting regression from their historic heights, from 40.8% from three to end November to 32.3% since would set a tone for the rest of their season. Smart, Brogdon and Jaylen Brown all allowed more than 1.20 points per possession while guarding opponents in isolation through 38 games.

It’s one of the more substantive struggles the team described earlier in the season, individual efforts on the defensive end. Boston improved to the ninth-ranked unit overall with a strong December, but did so inconsistently as lockdowns cancelled out letdowns. The last two games marked the low end of their efforts. Malcolm Brogdon told the Boston Globe the Celtics relaxed when the Thunder ruled out Shai Gilgeous-Alexander.

“We got our a** kicked,” Brown said. “When you come out and you take it for granted, that’s what happens. We probably had it coming to us. We came out the last couple of games, and we pick and choose when we wanted to play. We wasn’t connected, didn’t have each other’s back out there, no help side defense, we didn’t guard our yard.”

The Celtics described similar lapses in effort during their recent three-game losing streak. Tatum talked about not having fun on the previous road trip, Smart saw dejected faces and Brown bemoaned missed shots turning into bad defense. They leaned into the notion that they’re receiving their opponent’s best shots each night.

That may have been the case as the Thunder, who finished Tuesday ranked 22nd in offense, shot 59.2% from the field, 20-for-40 from three and generated 21 points on the fast break. Joe Mazzulla tried to praise the Celtics’ process early in their lull last month, said they stacked up more good possessions than in some of their wins earlier in the year and defended the group’s defensive growth. Suddenly, the loss in Golden State the Celtics asserted was just one of 82 turned into a bad month. Since, Boston sits at 27th in offense and 10th in defense.

“We have consistency,” Mazzulla said after the loss to Indiana. “I don’t think one half shows the habits that we’ve consistently been building, and I think it’s the only positive thing that we’ve had from an analytical standpoint during our tough stretch here over the last 10 games here … I don’t look to one half, the way we played in the second half showed that was even more of a one time (thing).”

The Celtics bounced back, as Mazzulla expected, with a four-game win streak, including resumé wins over the Bucks and Clippers. They’ve generally favored Mazzulla’s free-flowing offense and hesitancy to call timeouts in many cases. They’ve bounced back from their worst losses quickly, beating Dallas and Minnesota badly after falling to the Bulls in October and Indiana last month. Mazzulla emphasized the long game they’re playing, sitting Robert Williams III despite no pain or setbacks for left knee injury management in OKC.

The players need to support his approach with consistency and self-correction. They did a better job offensively over the last two games, since they shot 26.9% from three in first quarters over their last eight games, finding other spots on the floor to shoot from. Brown continued a nearly 30-game run of isolation and transition scoring. Tatum drew 10.4 free throws per game over that stretch as his three-pointer faded. They could not uplift their teammates though, with Derrick White, Sam Hauser, Brogdon and Smart all in major slumps.

Since the beginning of December, Brown and Tatum averaged 6.6 assists per game to 6.0 turnovers. Smart took on the brunt of the playmaking role and did an admirable job trying to speed up the offense and generate passing, but on some nights, the shooting struggles of others left him shooting more often. Brogdon, who is struggling to finish in the paint this year (48%), fell to 5-for-18 from the field to begin the road trip.

Defense defined this team last year. They ranked No. 1 in the aforementioned isolation stat (0.80 PPP allowed) and the Celtics began pivoting in that direction during December to survive their slump. Williams III’s limitations may prevent him from averaging 30 minutes. Mazzulla previously mentioned a return to the starting lineup being possible, and his decision, if it makes sense.

That’s one answer, others including a return to the rapid ball movement from earlier in the year. They ranked 23rd in half court points per 100 plays since the end of November. Another could include generating more rim looks, they remain 24th in shots per game at the rim.

In-game shifts help too, like when Mazzulla gave Blake Griffin a chance to guard Giannis Antetokounmpo on Christmas. Chalking losses up to energy, makes-and-misses, a few plays in crunch time or waiting to play better defense until Williams III plays more won’t alter their recent run.

“We’re not shooting the ball well, and human nature kind of lets that affect the defensive end,” Tatum said after the Denver loss. “The really good teams can counter that, and just figure out a way to win. We’re 26-11, so more often than not we have, but tonight just wasn’t our night.”