Why 2023-24 Celtics are one of the best NBA teams ever

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BOSTON — The Boston Celtics certainly benefitted from the absences of injured opponents in the Eastern Conference playoffs. And in the NBA Finals presented by YouTube TV, they didn’t have to face the defending champion Denver Nuggets, a team that out-executed the Celtics in two playoff-like regular-season meetings.

But, having dominated this league all season, the 2023-24 Celtics are simply one of the best teams of all time.

Here are some numbers on the Celtics’ place in NBA history …

1. All-time point differential

The Celtics’ final record (regular season and playoffs) of 80-21 ranks as the 13th best mark in NBA history. But over those 101 games, they outscored their opponents by an average of 10.7 points per game, a mark that ranks fifth.

Best point differential, regular season & playoffs, NBA history

The Celtics set a record by winning 19 games (17 in the regular season and two in the playoffs) by at least 25 points. They lost 21 games total, and only eight were by double-digits.

2. Top two on both ends of the floor

To be that good, a team must be great offensively and defensively. And the Celtics were just the fourth team in the 28 years for which we have play-by-play data to rank in the top three on both ends of the floor in the regular season, finishing first in offensive efficiency and second in defensive efficiency.

The teams they joined were the 2014-15 Golden State Warriors (second and first), the 2016-17 Warriors (first and second), and last season’s Celtics (second and second).

Of course, while those two Warriors teams both won championships, last year’s Celtics lost in the Eastern Conference finals. So they just returned and became the first team in these last 28 years to rank in the top four on both ends of the floor in two straight seasons.

Celtics coach Joe Mazzulla is an analytical guy, one who will tell us what his team’s expected points per shot were at any portion of a game.

“We live in an expected world,” he said after becoming the youngest coach in the last 55 years to win an NBA title. “So we didn’t pay much attention to the actual numbers.”

But Mazzulla wanted to make sure after coming up short last year that his team was better in the margins.

“It was just paying attention more to the process of what we were doing,” he added. “And there were obviously some things that we had to improve upon from last year analytically to make up for some of the stuff that we lost. The guys bought into that.

“So to me, it was just more of the process of making sure that we are playing the right way, making sure, you know, we are attacking the game analytically in the right way, but also having the open-mindedness and discipline to do some of the other stuff. I thought it was a good balance.”

3. NBA’s most efficient offense in history

The offense wasn’t just No. 1 in the league. The 122.2 points per 100 possessions the Celtics scored in the regular season was the highest mark in NBA history.

Shooting is the most important factor on offense and the Celtics’ effective field goal percentage of 57.82% was just a hair behind the Indiana Pacers’ mark of 57.85% for the highest in NBA history. But the Celtics — once known for having issues taking care of the ball — also had the league’s lowest turnover rate (12.1 per 100 possessions).

Of course, having the most efficient offense in NBA history doesn’t mean having the best offense in NBA history. Everything is relative, and league-wide, this was the most efficient scoring season ever.

But the Celtics’ offense still measured as the fourth-best offense in the 28 seasons for which we have play-by-play data when measuring how efficiently a team scored relative to the league average.

Biggest difference, points scored per 100 possessions vs. league average

Since 1996-97

Three of the other four teams above ranked no better than 15th defensively, while the 2015-16 Warriors ranked sixth.

4. Shutting down the Dallas offense

As noted above, the Celtics ranked second defensively. It’s possible they saved the best for last.

In beating the Dallas Mavericks in five games in the NBA Finals, the Celtics held the Mavs to just 106.7 points per 100 possessions. If you take away the Mavs’ last two regular season games (in which they rested both Luka Doncic and Kyrie Irving), the Finals were their worst five-game stretch of offense all season. And that includes a pair of extended stretches without Irving.

The Mavs’ effective field goal percentage (51.6%), free throw rate (22.4 attempts per 100 shots from the field) and offensive rebounding percentage (25.9%) in the Finals were all their worst marks of the four series they played in these playoffs.

The Celtics had a game plan to defend the Mavs one-on-one or two-on-two, they executed it brilliantly, and the Mavs never really forced them to adjust that end of the floor. Doncic’s usage rate (36.7%) was the highest of the Mavs’ four series, but his efficiency (true shooting percentage of 53%) was way down from the Western Conference finals (62.7%).

5. Clutch improvement

Even if a team’s overall point differential is historically good, it does need to win some close games. And the Celtics have been much better in close games over the last two seasons than the previous two.

Celtics’ clutch record, last four seasons (regular season + playoffs)

Clutch game = One in which the score was within five points in the last five minutes

This season’s 27-12 mark includes a perfect 6-0 in the playoffs. In winning 27 of those 39 games that were within five points in the last five minutes this season, the Celtics outscored their opponents by 20.8 points per 100 clutch possessions, with great numbers on both ends of the floor.

They turned a weakness into a strength, earned banner No. 18 and became one of the best teams we’ve ever seen.

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John Schuhmann is a senior stats analyst for NBA.com. You can e-mail him here, find his archive here and follow him on X.

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