Prior to that, Kornet got too close to Alperen Sengun, who made space to catch the inbounds pass and then beat Kornet to the rim for a go-ahead dunk with 10.3 seconds left.
“Those lose two plays were on me, those were my fault,” Mazzulla said. “I didn’t put us in the best matchups. I saw the plays they were trying to run and tried to change the matchups and put our guys in a tough spot. That’s a tough one because I thought our guys did everything to win the game.
“Our guys played great for 47 minutes and 30 seconds, and I didn’t help them close it at the end. I have to be better.”
The 114-112 loss wasn’t completely on Mazzulla. But it does expose a stubbornness that may need to be adjusted.
Thompson, the second-year guard, scored a career-high 33 points and got any shot he wanted because of his first step. Dillon Brooks, who made 88 3-pointers in his first 41 games, made a career-high 10 Monday and boosted his 3-point percentage by nearly two points.
They were essentially the Houston offense. The trio of Jalen Green, Fred VanVleet, and Alperen Sengun scored 30 points on a combined 9-for-32 shooting. The Celtics wanted to contain those three, but in turn they allowed Brooks and Thompson to dominate.
And this is hardly the first time an unheralded player or secondary scorer registered a career night against Boston this season. There’s Caleb Martin, Keegan Murray, Kevin Porter Jr., and Dejounte Murray, players who have punished the Celtics but weren’t primary on the scoring report.
Mazzulla’s philosophy is to let the numbers ride, bank that eventually those players will play to their percentages. Brooks made five 3-pointers in the first half — his career high for a game was six — so it was unlikely he would hit five more in the second half, but he did.
Thompson, who did not play in the Jan. 3 meeting in Houston, was an issue from the opening tip because of his speed. The Celtics had no one who could guard him individually but yet he kept getting open for buckets against single coverage.
And he scored 10 of his points in the fourth quarter and Mazzulla has to adjust to that.
This season’s reached a point where the Celtics have to realize that some role player is going to play over his head, and there are too many examples to call it happenstance. The Celtics have to adjust defensively. They should have paid more attention to Brooks, or shade another defender onto Thompson. They combined for 18 of the Rockets’ 29 points in the fourth quarter.
And while the Celtics stuck to their plan of containing three leading scorers, it still came in defeat. And it’s happened far too often this season.
“With the Brooks one, it’s tough,” Mazzulla said. “I thought we did a good job on the three guys that really get them going. (Brooks) was a difference maker for them. He hit some contested ones. It wasn’t like we didn’t adjust to them.”
But those adjustments weren’t enough. For example, Ime Udoka, who knows Jayson Tatum well, implemented a defense that was key in keeping him scoreless in the first half.
Tatum responded with 15 points in the third. In the fourth, Udoka decided to blitz Tatum each time he had the ball, limiting him to two shots in the final period.
He put the pressure on Brown and Jrue Holiday to beat them, and they finished 2 for 11 in the final period for 7 points. Brooks and Thompson had 51 points on 18 field goals after the third quarter, and Mazzulla needed to make some serious adjustments to ensure they didn’t get those same looks in the final period.
Instead, they went 8 for 10 in the fourth. That was the difference. Once Tatum got into a rhythm, Udoka decided to take the ball out of his hands. That caused the Celtics’ offense to sputter. The former Celtics coach put the onus on the Celtics to score in a sped-up offense and they faltered.
Mazzulla stuck with his pre-game strategy and it cost him.
“One, just take ownership with the guys,” Mazzulla said when asked how he plans to respond after taking responsibility for this loss. “(The players) are the ones out there battling and they put you in the position to win. And when you don’t help that, that’s a tough one — and that’s something that I’ve got to get better at.”
This was not one of those lack-of-focus losses. The Celtics were outgunned by a determined and rising team. But when players are constantly producing season-high or in this situation career-high nights, it becomes a you thing. Players are motivated to play the defending champs and that not only means the star players.
Two players who combined to average 26 points score 69 on Monday, and these breakout games are becoming a recurring issue that needs to be addressed with in-game adjustments.
Gary Washburn is a Globe columnist. He can be reached at [email protected]. Follow him @GwashburnGlobe.
