Simons made 6 of his 13 shots and lived up to his reputation as an offensive force. Defensively, he showed effort but struggled on ball, especially against Raptors rotation player Gradey Dick.

“I was a little nervous at first, but I think in the second half I calmed down and started to play my game a little bit more,” Simons said. “I was nervous about being back out there and a new team. [Mazzulla] didn’t say nothing about the fouls, but I knew I needed to chill out with the fouls.”

Simons rested in the preseason opener as Mazzulla went with four projected starters in the 121-103 win over the Grizzlies. This time he opted for Simons and Payton Pritchard, who scored 19 points. Chris Boucher, in his return to Toronto after seven seasons with the Raptors, scored 19 on 7-for-10 shooting.

Looking for more consistency, especially with rebounding, Mazzulla deployed his players in hockey-type shifts, pulling all five players from the floor when they couldn’t collect a defensive rebound. In one sequence, he pulled rookie Hugo González after less than a minute, then threw him back into action with the next shift.

There were several occasions in the first half where players logged less than a minute but eventually returned to the game. Boston ended the half on a 20-3 run sparked by a Pritchard heater for a 63-42 lead.

The Celtics led, 103-89, with 3:45 left before a disastrous final stretch where they committed eight turnovers and were outscored, 18-2. Mazzulla used Baylor Scheierman and the two-way contract players, and they struggled to even get the ball up the floor.

“That’s good,” Mazzulla said of the experience for the rookies. “Those guys have to get those reps. They have to be able to execute. They have to understand every possession matters. I thought Toronto did a good job turning up the pressure and we have to continue to work through executing. Whoever it is out there.”

The Celtics, who rested Jaylen Brown, Derrick White and Sam Hauser, finished with 29 turnovers, 21 in the second half.

. . .

Mazzulla was not pleased with Scheierman early in the fourth quarter Wednesday against Memphis and the second-year swingman struggled against the Raptors, with six fouls and five turnovers. In the first two minutes of the final period against the Grizzlies, Scheierman committed two live-ball turnovers (Mazzulla’s absolute most-despised error) and missed three contested 3-pointers.

After the third miss, Mazzulla looked back at his bench and told his assistants he couldn’t watch anymore, replacing Scheierman with training camp invite Jalen Bridges. Ninety-eight seconds later, he reinserted Scheierman, who then responded with a rebound and step back 3-pointer. Mazzulla screamed at his second-year player, “Welcome to the game!”

More is expected from Scheierman in his second season as he vies to fill an energy and defensive role on the second unit. Mazzulla said that growth will be a process.

“He’s a smart guy and he plays really hard,” Mazzulla said. “But that segment was an important segment for a young player to understand, especially at the start of the fourth quarter. Those momentum swings regardless of the game, you have to play really hard, but you also have to have situational awareness. Those are the things you really have to grow at as a player and as a team because a 20-point lead at the start of the fourth quarter, as we know, means absolutely nothing.

“But he’s great, wants to be coached, plays really hard. Last year he did a great job of delivering in that Brooklyn game at home. That was the breakout and now the expectation is to do it every night and do it physically and also mentally.”

. . .

Mazzulla was annoyed by a report that indicated González, who is multilingual and speaks Spanish as hisprimary language,was having trouble comprehending English during training camp. González told reporters last week after practice he was learning the language of the offense, which was misinterpreted as English.

“Who reported that he was having language barriers?” Mazzulla asked. “Someone put that out there. He’s not. He speaks multiple languages and I think people should speak to him in his native language. For anybody in the media that can speak Spanish, you should talk to him in Spanish. I didn’t like that headline because he doesn’t have an issue understanding that. I was pretty [upset] about that.”

Gary Washburn is a Globe columnist. He can be reached at gary.washburn@globe.com. Follow him @GwashburnGlobe.