Joe Mazzulla repeats crucial mistake in Celtics Game 6 loss to 76ers

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Joe Mazzulla repeats crucial mistake in Celtics Game 6 loss to 76ers | Brian Robb

Brian Robb · MassLive

Fri, May 1, 2026 ·

3 min read

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PHILADELPHIA — The biggest blind spot for Joe Mazzulla as a coach has always been adjustments in the postseason. The Celtics coach has been slow to tweak during his four years at the helm in Boston . Sometimes (2024), the roster has been good enough where it hasn’t mattered. Other times (2023, 2025) it has led to some stunning upsets against the Heat and Knicks .

The Celtics are facing a potentially historic collapse on Saturday after dropping Game 6 to the 76ers Thursday night at Xfinity Mobile Arena. Boston has blown a 3-1 series lead and could become just the 14th team in NBA history to lose a series after holding that commanding advantage.

A lot of things went wrong for the Celtics in Game 6. Jaylen Brown played out of control and showed bad shot selection. The starting unit remained sluggish offensively. Boston got no real offense out of their top two bigs. It was a lot of what we saw in Game 5 for Boston. Yet Mazzulla made no notable changes until the game was already decided in the fourth quarter, when he pulled all starters to rest their legs for Game 7.

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Things were supposed to be different for this Boston team in 2026. A deep roster allowed Mazzulla to mix and match with lineups throughout the regular season. However, that mentality has faded away for Mazzulla during this series. Just like last season when he stuck with Kristaps Porzingis for far too long, his Achilles’ heel is being put on display yet again.

Boston’s starters have been a net negative all series, but he stuck with that group again for extended parts of Game 6 after a Game 5 dud. Sam Hauser remains a strong candidate to be replaced by Jordan Walsh or Baylor Scheierman . Nikola Vucevic was a mess on both ends, but still got his usual minutes despite his struggles. A small ball lineup has not been used all series long despite the fact that it had been a successful weapon for Boston with Tatum back in the fold to close the regular season.

“We definitely made some adjustments,” Mazzulla said after Game 6. “Some of them worked, some of them didn’t. Like I said, I thought tonight the Sixers played well, and we didn’t.”

While there may have been tweaks, a lack of them involving personnel was noteworthy. Now, the Celtics are on the verge of squandering a golden opportunity in a wide-open Eastern Conference. Simply relying on the players to figure things out does not look like the answer this time around against a Sixers team that has talent and momentum. Nick Nurse is outcoaching Mazzulla in this series and if that trend continues, Boston will be going home.

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