Players such as Jaylen Brown and Jayson Tatum pointed to more consistent effort as the goal after a stretch of six losses in 13 games. Mazzulla said a "lack of effort' wasn't the problem.

The Celtics responded with a 125-71 win over the Toronto Raptors, ending their month 8-6 before a four-game road trip against Western Conference teams.

"It's not a lack, it's just inconsistent effort at times," he said. "It just comes with the season. I think there are times in the past and there's going to be times where you have to work through it and you've got to fight to even be more consistent."

Mazzulla said he believes the Celtics are getting an inaccurate tag of lacking effort on defense while slumping on offense. He thinks defenses can also put forth maximum effort but slump.

"It is so easy to blame effort as opposed to just make a shot," he said. "You know our expected defense is No. 1 in the last 10 games. Our layup percentage defense is No. 1 in the last 10 games. And our expected points per shot defense is like No. 3 in the last 10 games. But you know what our 3-point percentage is? 28th.

"We've got to play better on both ends of the floor. We've got to hit shots. We're just going to continue to stick to the process of the details and the effort and the execution of our system on both ends of the floor."

Despite the overwhelmed opponent Tuesday, Mazzulla maintains the Celtics didn't execute on several possessions, which makes the difference between wins and losses.

"There's 10 to 12 possessions per game that we have to be better on the defensive end of the floor," he said. "I want to be 100 percent clear on that. But it's very easy when things aren't going well to blame defense, effort. It's very, very hard to let your brain or your heart rest in we've just got to be better offensively. You have to fight those two things."

Jrue Holiday returned to the lineup Tuesday after missing the past three games with a right shoulder impingement and scored 14 minutes in 25 minutes. Holiday last played on Dec. 23 in the loss to Orlando and said the injury spurred from getting hit on a screen and just worsened over the next few days.

"Probably," Holiday said when asked if the injury could linger. "But I think it's manageable. Great training staff here and they've already done a great job of getting the treatment that I need to even come out there and play [Tuesday]."

Kristaps Porzingis missed his third consecutive game with a left ankle sprain sustained in the Christmas Day loss to the Philadelphia 76ers. Porzingis was walking around the locker room without a brace but it's uncertain when he would be available for the four-game road trip beginning Thursday.