The Boston Celtics' postseason hopes took another devastating hit this week, falling to the Philadelphia 76ers in a stunning first-round collapse. For head coach Joe Mazzulla, it's a familiar—and troubling—story.

Later this month, Mazzulla could very well be named NBA Coach of the Year. But that honor would only highlight the glaring gap between his regular-season brilliance and his postseason struggles. Since taking over in Boston, Mazzulla has posted a jaw-dropping 238-90 record (.726 winning percentage), the best in NBA history over a four-year span. He's won 56 or more games every single season—a feat that puts him among the league's elite.

But when the playoffs arrive, the script flips. Outside of Boston's 2024 championship run, the Celtics have suffered three ugly postseason upsets under Mazzulla's watch. This year's 3-1 series collapse to the 76ers is just the latest chapter in a pattern that's growing harder to ignore.

Let's rewind to some of the key moments that define Mazzulla's postseason track record:

Game 4 vs. Philadelphia: A clock management nightmare
The Celtics had the ball with 17 seconds left in overtime, trailing by one. No timeout was called. Instead, Jayson Tatum dribbled out most of the clock before passing to Marcus Smart, who couldn't even get a shot off before the buzzer. Mazzulla didn't admit it was a mistake until the next day.

Game 6 vs. Philadelphia: Marcus Smart calls out the coach
Facing elimination, Mazzulla waited too long to switch back to a double-big lineup featuring Al Horford and Robert Williams—a combination that had been essential to the team's success all season. Smart, never one to hold back, publicly called out the delay.

These aren't just isolated errors—they're part of a worrying trend. When the stakes are highest, Mazzulla's decision-making has consistently come up short. For a team with championship aspirations, that's a problem that won't go away with a regular-season award.