DETROIT — Sam Hauser learned about 90 minutes before tipoff on Monday that he was going to make his first NBA start. That opportunity appeared to jumpstart the struggling swingman, who delivered one of his better games of the season.
After averaging 6.7 minutes over the past four games, Hauser stepped into his starting role and flourished with 15 points — all in the first half — in the Celtics’ 111-99 win over the Pistons at Little Caesars Arena.
Hauser, who had shot 29.7 percent from the 3-point line in his previous 29 games, lifted the Celtics in the first half, his shot whistling through the nets similar to his November hot streak. The five 3-pointers made were his most since Nov. 16 in Atlanta.
“That was my first start ever in the NBA, which was a pretty cool moment for me,” he said. “You’re able to get in a rhythm real quick when you start a game.”
Hauser shot 47.9 percent from the 3-point line in his first 22 games this season, emerging as a critical part of the Celtics’ bench. But the prolonged slump cost him playing time, so he said he was stunned when coach Joe Mazzulla chose him to start in place of Jaylen Brown, who missed the game with a non-COVID illness.
“I thought [Hauser] was great in the first half,” Mazzulla said. “Just [like] with all our guys, I trust his work ethic; I trust his mindset. I thought it was a good opportunity for him to play and for us to get into a different flow on the offensive end. I just watch him work every day and all those [reserve] guys and I know they’re ready.”
Hauser said he’s tried to maintain his confidence and his shooting routine through his slump.
“I don’t think anything mechanically was wrong with my shot,” Hauser said. “They just really weren’t going down. I set a pretty high bar for myself to start the year. When you start not making as many as before, it starts turning some heads. Overall, just sticking to the grind and working through it. Just trying to build off of this for sure.”
Brown passed on optional shootaround to get treatment Monday morning but was scratched hours before tipoff.
Brown was listed as questionable early Monday afternoon and Mazzulla said the illness is legitimate. But the scratch also lends to speculation that Brown could be involved in potential trade talks before Thursday’s deadline.
“He’s sick,” Mazzulla said. “I’m not sure [when he became sick]. I know he got some extra rest today to try to be able to play. He doesn’t feel [up to it].”
The Nets officially announced their trade with the Mavericks, sending guard Kyrie Irving and forward Markieff Morris to Dallas for forward Dorian Finney-Smith, guard Spencer Dinwiddie, and a package of first- and second-round picks.
There has been speculation the Nets would consider moving superstar Kevin Durant, who made a trade request this summer which he later rescinded.
The Celtics were also without Luke Kornet and Marcus Smart (the latter for the seventh consecutive game) with sprained ankles. Mazzulla opted to give Hauser his first NBA start along with Derrick White at point guard.
The Celtics are coming off one of their worst offensive performances of the season in scoring 94 points against the Suns.
“I thought we had some empty possessions offensively,” Mazzulla said. “We were inconsistent on both ends of the floor. [We need to] just continue to be consistent throughout the entire game and win transitions. Win the end of quarters. Win the start of quarters. Win the transition game.”
Mazzulla has emphasized consistency and focus offensively. The Celtics jumped out to a 7-0 lead against the Suns, then allowed the next 12 points and lost their grip on the game.
“Keep our focus on what is the difference maker for us as a team,” Mazzulla said. “For me, on the offensive end it’s our spacing and how we make decisions in the details regardless of who we are playing that are important to us. When we are at our best we do a good job of doing those.”
The Celtics started Monday trying to push the ball, seeking open threes. Six of the first 11 shots were 3-pointers, including two by Hauser, who has been slumping. Mazzulla wants more up-tempo play.
“I think it’s a little bit because our pace has slowed down,” he said. “We don’t get those early offensive attacks like we used to. I thought in the Brooklyn game we did a good job of getting early attacks, and then we did a better job of attacking late in the shot clock. It’s about doing both those things and not having as many empty possessions in the middle of the shot clock.”
The Pistons also have players involved in trade rumors, including swingman Saddiq Bey and backup center Nerlens Noel. Coach Dwane Casey said he tries to use the deadline period as motivation.
“The only comment I made was a few days ago: If your name is involved it means you’re respected around the league,” he said. “Young players don’t understand that but older players do. I don’t think our guys are affected by that, our younger guys especially. They know they’re a part of the core.”
With Kornet out, the Celtics recalled Mfiondu Kabengele from G-League Maine for more big depth. Meanwhile, former Piston Blake Griffin saw his most meaningful minutes in weeks when he checked in for Al Horford in the first period. … Mazzulla said Smart is improving but gave no indication when he may return. The Celtics have five more games before the All-Star Break and there’s consideration of shutting Smart down until after the break. The Celtics open the unofficial second half Feb. 23 at Indiana, meaning Smart would have more than a month of rest.
Gary Washburn is a Globe columnist. He can be reached at firstname.lastname@example.org. Follow him on Twitter @GwashburnGlobe.