The Celtics overachieved all season, but their collapse against the 76ers raises big long-term questions

Trading for Giannis Antetokounmpo may seem like the obvious answer, but it's not that easy

Sam Quinn

May 2, 2026

10:36 pm ET

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19 min read

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Turn the clocks back to October. Jayson Tatum was recovering from a torn Achilles and expected to miss the season. Half of last year's rotation was gone. There were corners of the internet that expected the Boston Celtics, like the Indiana Pacers, to take a gap year. From that perspective, making it to Game 7 of a playoff series, any playoff series, could be viewed as an organizational win. This shouldn't feel like the disappointment it so obviously does.

The Celtics are a victim of their own success. Had they won 46 games instead of 56, no one would care how their season ended. Instead, Jaylen Brown had a career year. Spreading the gospel of Derrick White became the cause célèbre of the basketball nerd community. Tatum made a historic return from that Achilles tear. Boston quickly cemented itself as Eastern Conference favorites and even got to start their playoff run against their frequent postseason punching bag, the Philadelphia 76ers, whom Tatum and Brown had already beaten in three separate playoff series. The 76ers were supposed to be a stepping stone to a far more meaningful rematch with the Knicks, a matchup that felt almost preordained when Boston took a 3-1 series lead.

That was six days ago. After Philadelphia's Game 7 win on Saturday night, Boston's season is over. Three straight losses, two of which Tatum took part in, turned a once-promising season into a borderline disaster. Ironically, a gap year would've made for a simpler offseason. You can hand-wave away bad losses when you're not trying to win. But the Celtics spent a whole year convincing the world and probably themselves that they still were very much capable of winning not just in the regular season, but in the playoffs. Losing to a Play-In team, especially this Play-In team, raises serious questions.

Boston has been kicking Philadelphia's ass for going on a decade now. If the Celtics are suddenly vulnerable against them, does it mean they're vulnerable against everyone else? Are these minor, fixable flaws, or do they need to consider something more drastic to address all of this? Let's try to figure out what went wrong here and what steps are needed to get the Celtics back on track for genuine championship contention.

Boston's math problem

The Celtics are built to win the math problem. The fundamental principle on which they are built is that if they get to take more shots than their opponent, and if those shots are higher-value shots than the ones their opponent is taking, then they should win far more often than they lose. They attempted 283 more total field goals than their regular-season opponents because they had the NBA's third-highest total rebounding rate and third-lowest offensive turnover rate. They had the league's fourth-highest 3-point attempt rate a year after becoming the first team ever to shoot more 3s than 2s. More shots and better shots tend to lead to more wins. If a playoff series lasted 10,000 games, Boston would almost always win it.

Of course, it doesn't. The playoffs are a much smaller sample and, therefore, much more prone to variance. The Celtics relearn this almost every spring. Look at their losses against Philadelphia. Boston shot below 30% on 3s in all four of their losses to Philadelphia. That probably sounds familiar. The Celtics shot 25% from deep in Games 1 and 2 of the Knicks series last year, two games in which they blew 20-point leads. In the 2023 Eastern Conference Finals against Miami, in which they fell behind 3-0, they shot 30.3%.

That's three series the Celtics lost as heavy favorites because the 3s stopped going in. This season as a whole, the Celtics went 44-6 in games in which they made 35% of their 3s, but 15-24 in games that they didn't, as noted by Yahoo's Kevin O'Connor. Boston doesn't have another pitch offensively. They scored the fourth-fewest points in the paint in the regular season, and no one had a lower free-throw rate. Meanwhile, their possession advantage tends to shrink in the postseason. Mitchell Robinson and Karl-Anthony Towns killed them on the glass in the Knicks series last year. The 76ers turned the ball over almost as rarely in the regular season as the Celtics do, and did so less in this series. Suddenly, Boston isn't taking more shots than its opponent and, while the shots they do take are more valuable on paper, they're not nearly as stable in a playoff setting.

If Joe Mazzulla has a weakness as a coach, it's how stubbornly he tends to cling to his big-picture vision. If Boston had attempted to minimize variance with its huge leads against the Knicks last season by taking shots that were perhaps less valuable but ultimately easier to make, that series was winnable. Game 2 of this