The Whiteboard: The Boston Celtics offense looks broken

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The Boston Celtics dropped to 7-8 on Wednesday night after a 110-99 loss to the Atlanta Hawks. Jayson Tatum poured in 34 points but it was the sixth time this season and the third game in a row in which the Celtics failed to score 100 points. It’s been a rough start for Boston and their offensive struggles have been front and center as they approach the end of the first quarter of the season.

Last year, the Celtics were a top-10 offense, scoring an average of 113.1 points per 100 possessions. There has been a league-wide drop in offensive efficiency this season, but Boston has been hit particularly hard, dropping to 23rd and managing just 104.6 points per 100 possessions.

Some of this can be traced to roster changes — Dennis Schroder and Josh Richardson have replaced Evan Fournier and Kemba Walker, Al Horford has taken the minutes that went to Tristan Thompson and Daniel Theis last season. And Boston has already been hit by COVID exposure again, with Jaylen Brown missing seven games and both he and Tatum talking openly about lingering effects. But they also look like a team that has found stagnation to be their dominant offensive identity.

Earlier this month, Marcus Smart called out Jayson Tatum and Jaylen Brown in frustrated post-game comments, saying, “I think everybody’s scouting report is to make those guys try and pass the ball. They don’t want to pass the ball and that’s something that they’re going to learn.”

The specifics of his comments can be debated, but the context is rock solid. So far this season, the Celtics have been averaging 12.3 isolation possessions per game, 10.8 percent of their total offensive possessions. And that number may even be a little low because it only includes possessions that were finished (with a shot, turnover or shooting) with isolation — there are certainly some additional possessions where isolation was the dominant action but the play ended in a kick-out or pass to another shooter. For reference, 12.3 isolations per game would be the sixth-highest team mark for the seven seasons for which NBA play type data is available and the highest mark for any non-James Harden or LeBron James team.

And of course, the most important factor here is that the Celtics haven’t been scoring efficiently out of isolation, increasing a portion of their offense that’s generating worse returns. It’s all part of a larger pattern of stagnation, with dramatically decreasing ball and player movement, something that’s painfully obvious if we compare their offensive style chart from this season to last.

Last season, the Celtics ranked in the 49 percentile in ball movement and 42nd in player movement. Their marks from this season would rank in the 17th and fourth percentiles, respectively.

Jayson Tatum appears to be playing to his worst tendencies for the Celtics this season

Jayson Tatum is an incredibly special offensive player and he’s just one part of the larger offensive framework in Boston, but the shifts in his own play and decision-making this season are characteristic of the larger shifts. He’s averaging 6.1 isolations per game (22.2 percent of his total offensive possessions), up from a previous career-high of 4.7. His free-throw rate is the second-lowest mark of his career and a quarter of his shot attempts have been long 2-point jumpers.

He’s also averaging just 0.74 points per possession on post-ups — a career-low on what had been a fairly reliable weapon in previous seasons, in large part because so many of these post-ups have turned into fadeaway jumpers.

You can (cherry) pick a handful of representative plays but this one works nicely. Tatum dribbling through a sloppy pick-and-roll kicking the ball out and then relocating to the elbow only to retreat for a pull-up jumper 20 feet from the basket. All with four teammates essentially standing still.

It’s not just Tatum. Schroder is averaging 3.2 isolations per game, his highest since 2017-18, his last in Atlanta. When he’s been on the court, Jaylen Brown has averaged more than two isolations per game for the first time in his career. They just look like a team that’s not sure how they want to create open shots other than relying on the individual scoring advantages of Tatum, Brown and Schroder.

Things could look better as they build a rhythm with Brown back on the court and new head coach Ime Udoka exploring more ways to build and implement an efficient system out of these pieces. But things could also go the other direction — struggling along at .500 with an offense that’s making everything look and feel much harder than it has is a recipe for fractured chemistry and mounting frustrations.