BOSTON — Payton Pritchard admitted he was “disappointed” in his past two games. Even those close to him wondered what was up as he put together uncharacteristic performances. There was too much second-guessing and deliberation for a guy who often talks about his endless confidence.

So, after Pritchard woke up Wednesday, he got back to the basics: He went to get a haircut. He got back to his routine. And it all worked. Pritchard was everywhere as the Celtics blew out the Grizzlies. It’s not the first time — nor will it be the last — that he feels mentally like he’s in a funk. But he explained how on the other side of those struggles is an opportunity for growth.

“I actually have gone through it a lot,” Pritchard said. “And to be honest, when I go through them is usually when I kind of break through and get a little bit better. I went through it in college, and I’ve gone through the pros a lot.

“My fourth year, when I started playing again after I just signed a new contract, I think I went through a five-game stretch I didn’t hit a 3 or even have a bucket. ... I was really down that time. But then getting through it, once I got through it, I started to get better and better and better. So there’s going to be low points, and it’s just — don’t let it break you. You just grow from it, learn from it and get better from it.”

It was an honest admission from Pritchard, a guy who hasn’t always been vulnerable about some of those struggles. In the past, he’s spoken about having confidence and still believing in the process. But it’s also natural to get down when shots aren’t going and slumps continue.

A freshly-cut Pritchard was impactful as he finished a whopping plus-42 in 30 minutes against the Grizzlies. He finished with a team-high 24 points, adding six rebounds and nine assists. Plus, the shots went down: 8-for-15 from the field and 5-for-10 on 3s. There was no hesitation before putting up a shot as he let them fly from everywhere.

“I was just kind of in a funk mentally,” Pritchard said. “Just didn’t play with the same juice, same energy. No pace. ... Just had the mindset that I was going to come in. It wasn’t about the scoring, but when I got the ball, push it as fast as possible. Attacking. Just playing that way.”

The Celtics are at their best when Pritchard is playing with that aggression. When he won Sixth Man of the Year last season, he often subbed in and immediately started letting shots off. His role has changed now that he’s a starter, but the C’s still need him to be a consistent threat with and without the ball.

“Everybody kind of has their own way of getting through slumps and getting through tough times,” Derrick White said. “P knows we got the ultimate amount of trust in him that this is just a little slump, and we keep getting those looks that he’s been getting that will start turning for us.”