WALTHAM, Mass. — Jaylen Brown now considers himself one of The Unbothered.

As one of the top NCAA recruits in the country, he heard the criticism when his freshman year at the University of California did not live up to the loftiest expectations of some.

He heard the comments about his shot, his ball-handling, his perceived lack of elite basketball skill coming into the 2016 NBA Draft. He knew there were those who thought the Celtics reached when they took him No. 3 overall.

He couldn’t escape the statistical comparisons to some of his fellow lottery picks that left out the fact they were playing on lottery teams when he was fighting for minutes on the top seed in the Eastern Conference.

“I put too much energy into trying to prove other people wrong instead of trying to prove it to myself,” the second-year wing player said after Saturday’s practice. “All of my energy is focused on me right now. It’s on me getting better instead of putting energy out to change people’s mindsets and all that.”

He calls it The Unbothered.

“This year I’m so unbothered, it’s crazy,” he said. “This year I am just trying to be the best version of me. I know Celtics fans have high expectations and I am OK with that.

“I am unbothered, coming out and playing, knowing that I have abilities not a lot of people in this world have. I am going to show that this year.”

Brown spent a lot of time his rookie season being sensitive to other people’s expectations. Some of it was responding to criticisms. But much of it was also knowing, and accepting, his role on a veteran-laden team. While fellow lottery picks were afforded the chance to make mistakes and be the center of attention with their respective franchises, Brown was careful to largely keep his head down and be respectful of veterans.

As one of only four players back this season, he said he feels more at liberty to speak his mind and seek a position in the team hierarchy.

“Last year we had established roles,” he said. “We had a team where a lot of the guys were coming back. I had to get where I fit in. This year is an open field. We have 11 new guys. Everything is new.

“So I have a lot of opportunity. Me being here from last year, on a team that went to the Eastern Conference finals, allows me to have some form of leadership. I take that, embrace that.”

Brown said he is “100 percent more confident” in his second year knowing the expectations of Celtics coach Brad Stevens. The coach agreed that has been evident early in training camp.

“Jaylen has put in a lot of time,” Stevens ssaid. “You can see that. He’s just more comfortable than he was at this time last year. I think one of the biggest challenges for guys in their first through fourth years is that these guys are still trying to work to move on to the next role. It’s really just about doing what you do better.

“He’s doing that. He’s making open shots. He’s doing a good job defensively. Nobody will be harder on him on that end than I will be because ultimately I think that’s a huge, huge part of our team with what he does defensively for us.”

Stevens has said Brown has the potential to be a “lockdown defender” for the Celtics and that he will guard small forwards, shooting guards and point guards with the ability to switch onto power forwards as well.

“It’s challenging,’ Brown said. “Guarding (point guards and shooting guards) in the league, it’s not easy. Summer league was my first real go at it. It’s one of the things I’ve really tried to work on.

“It takes a lot of energy — especially being a big guy at 230 pounds chasing little guys around. But I am more than capable of doing it.”

Marcus Smart — arguably the team’s new defensive leader with the departures of Avery Bradley and Jae Crowder — echoed that belief on Saturday.

“It’s his athleticism and his ability to guard bigger guys and move with the smaller guys,” Smart said. “He’s real athletic. He can be a great defensive player. It’s all about ‘want to’ when it comes to defense.

“Anybody can play offense. But it takes a lot to get down and guard someone for 24 seconds. Then come back and do it possession after possession. Jaylen has that ability.”

Brown has long been a firm believer in his own abilities. It’s just now he claims he is far less interested in what others believe about them.

It’s one of the benefits of being one of The Unbothered.

“I don’t really care what people say anymore, to be honest,” he said. “Now it’s about proving it to myself. If I am about trying to prove people wrong, I’ll be proving people wrong for the rest of my life.”

-- ssouza@wickedlocal.com

On Twitter: @Scott_Souza