Joe Mazzulla is far from the only reason that the Celtics choked away a 12-point fourth-quarter lead Friday night and are now in an 0-2 hole in the Eastern Conference Finals.
The players on the court needed to be a lot better. Jayson Tatum didn't hit a single fourth-quarter field goal for a second straight game and committed two of his five Game 2 turnovers in the final 10 minutes. Jaylen Brown shot 1-of-5 from the field in the fourth and also gave the ball away twice, once on a travel and once with a forced shot into three bodies that was easily blocked. Grant Williams challenged Jimmy Butler face-to-face, but couldn't back it up as Butler drained one shot over him after another.
As Tatum said after the game, "Joe ain't miss no shots tonight. He ain't have no turnovers. I missed shots. I had turnovers."
Still, Mazzulla did make one critical mistake, and his defense of that mistake after the game made it even worse.
Mazzulla stuck with Al Horford down the stretch over Robert Williams, even though Horford struggled mightily at both ends of the floor Friday while the Celtics' best stretches of the game came with Williams on the court.
Horford once again couldn't hit a shot, shooting 1-of-5 from the floor and 0-for-3 from three. Over the last six games, he is now shooting 25% from the field (10-of-40) and 17.2% from three (5-of-29). He also got bullied by Bam Adebayo, who had 22 points and 17 rebounds on the night, including eight points and eight rebounds in the fourth quarter alone.
Williams, meanwhile, was 5-for-5 from the field Friday night and also got to the free-throw line four times, making three of them. He was a plus-7 for the game, making him one of four Celtics to finish in the positive in Game 2 along with Jayson Tatum (+5), Malcolm Brogdon (+10) and Derrick White (+8). Horford was a minus-15, second-worst behind only Brown (-24).
As The Ringer's Brian Barrett pointed out, the Celtics were dominant with Tatum and Williams on the court together in Game 2, not just defensively but offensively as well. The high pick-and-roll with those two produced arguably Boston's best offense of the night. Yet, Williams was on the bench for seven straight minutes down the stretch, even though he had scored seven of the Celtics' first 10 points in the fourth.
And as MassLive's Brian Robb pointed out, Mazzulla never once in the second half went back to a five-man unit of Robert Williams, Grant Williams, Tatum, Brogdon and White that was a plus-16 in seven first-half minutes.
When asked after the game if he considered closing the game with Williams instead of Horford, Mazzulla's answer was simple: "No."
Why not?
"Al's finished every game he's played," Mazzulla said.
And therein lies the problem. Mazzulla went with Horford because that's just what he always does. It's worked before, so no reason to change. But in doing so, Mazzulla ignored what was actually happening on Friday night, because what was actually happening was that Williams was having a much better game than Horford, and the Celtics were better when Williams was on the floor.
It's not like Mazzulla didn't make any adjustments at all in Game 2. He did go away from the double-big lineup to open the second half when that clearly wasn't working anymore. He also got Grant Williams back in the rotation, which paid off most of the night until Jimmy Butler began to torch him in the fourth quarter.
But in crunch time, when it matters most, Mazzulla – much like his players – crumbled, actively making the situation worse. He isn't the only reason the Celtics lost, but he certainly didn't do enough to help them win either.
