Celtics guard Jaylen Brown, right, defends Heat forward Caleb Martin during the Eastern Conference finals in May. Brown expects the Celtics continue to play tough defense despite the loss of Marcus Smart and Grant Williams. Rebecca Blackwell/Associated Press

Jaylen Brown didn’t hide his feelings about how much he’ll miss Marcus Smart after the Celtics traded their beloved point guard last month.

“My brother and my teammate and one of my best friends is not on the team anymore,” Brown said this week at his press conference to announce his contract extension. “Everybody knows it. I learned so much from Marcus. Marcus has been somebody that’s, like, we butted heads at times, we fought, we did it all, we put each other in headlocks. The journey won’t feel the same without him, to be honest.”

But as much as the Celtics will miss Smart, Brown doesn’t want his departure to be an excuse next season.

Among the most notable things Brown said on Wednesday was his desire for the Celtics to improve defensively after they lost their identity on that end of the floor last season. Without Smart – the 2022 Defensive Player of the Year – and Grant Williams, who was one of the Celtics’ most versatile defenders, Boston has gotten weaker defensively this offseason, at least on paper.

But Brown – with his words – did his best to set the defensive tone for the Celtics in July when asked a question about if the Celtics can compete for a championship next season.

“Of course. I’m excited to get started with the journey as well,” Brown said. “I think what Kristaps (Porzingis, acquired in the offseason) can bring to us defensively and the additions some of our other guys can bring to us defensively, I want to make sure that’s where we hang our hats this year and that starts with me, that starts with Jayson (Tatum), that starts with guys, Rob (Williams). With Marcus gone, we don’t want our defensive identity to go out the door as well, so we have to really emphasize that at the start of training camp.”

While the Celtics finished last regular season second in the NBA in defensive rating, Coach Joe Mazzulla acknowledged there was inconsistent play and they’ll have to reinvent themselves a bit with a changed roster that includes the 7-foot-3 Porzingis. He indicated that there will be more double-big lineups.

“You have to commit to it daily, you have to talk about it,” Mazzulla said. “But at the same time we’ve had multiple systems. This team and organization has always been built on defense and so a few years ago when we played double big there was a bunch of maintaining and a physical way to play. When Ime (Udoka) came and last year we were able to do some switching and so I think we have an opportunity to kind of blend both of them to where we do maintain our system and do some of the things we did well for the majority of the season and then just kind of reinvent and find small ways that adhere to our roster.”

HEALING FOR BROGDON: Mazzulla said that Malcolm Brogdon – who suffered a forearm strain in the Eastern Conference Finals – is recovering well and should be ready for training camp, but there’s apparently been some emotional healing for the Sixth Man of the Year after he was part of the initial trade for Porzingis before the Celtics pivoted to and dealt Smart.

“The organization has had a few conversations,” Mazzulla said. “I think any time you are in a situation like that and you are in a relationship, you just have to take some small steps into it. There is a healing process, there is a listening process and to see where we are at and where we have to get to. We’ve had some conversations as an organization but at the same time, we understand that the situation that it was and as the healing process goes on, we will move forward as well as you can.”

IN CASE THERE was any doubt, Mazzulla confirmed that Derrick White will step in as the Celtics’ starting point guard.

“We have the ability to play in different ways,” Mazzulla said. “We have the ability to play small and play big so with some of the changes that we’ve made so it opens up a lot of opportunities for Derrick, Payton (Pritchard) and Malcolm. I think that’s really important that those three have an opportunity to grow them and help them on both ends of the floor. Those three guys at the guard spot is a part of our identity and a part of what we need to get to on offense and defense.”