By Matthew Geagan, CBS Boston

BOSTON (CBS) — When Jaylen Brown signed a four-year, $115 million contract extension with the Celtics in October, he knew what was coming. The fourth-year guard knew the expectations would go through the roof, and that he’d have to put a tough 2018-19 season behind him.

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He also knew that his doubters would be louder than ever. And they were, taking to social media to shout how much the 23-year-old wasn’t worth his contract, laughing at the Celtics for making such a large investment on an unproven player.

Brown’s play so far this season has proven those doubters wrong, and he has another message for them to hear: The best has yet to come.

“I kind of anticipated it,” Brown said of the criticism of his new deal in a lengthy sitdown with Taylor Rooks for Bleacher Report. “I think most people thought I peaked in my second year in the league. I didn’t peak at 21. I’m only going to get better from here. Certain people think I’m playing out of my mind now because they didn’t expect it.”

On this year’s Celtics, Kemba Walker leads the way, Jayson Tatum makes it look so easy sometimes, and Gordon Hayward may be the team’s best all-around player when he’s on. But Brown has been Boston’s most consistent player on both ends of the floor this season, and he’s taken his offense to a whole new level, averaging 20.2 points per game off 49.5 percent shooting from the floor and a 38 percent clip from three-point range.

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To get where he is today, Brown had to escape the demons of the 2018-19 Boston Celtics that haunted him. The team struggled out of the gate, and Brown didn’t play well. He was sent to the bench early in the season, a move he accepted but didn’t agree with. That was just part of a drama-filled season that ended poorly for the Celtics, a season filled with closed door meetings every other week and plenty of time spent playing the blame game.

Brown reiterated that there were too many cooks in the kitchen for the Celtics to be successful last season. His own struggles and those of the team sent him into a funk, both on the floor and emotionally off of it.

“It took a lot to get out of that,” he said. “For me, I like to isolate myself sometimes. Not being around people was my way of dealing with things, and that’s not the best way to deal with stuff. Family and friends are necessary; talking about it to people or having someone to vent to, or someone to lift you up, can be good.”

But following an offseason that saw Kyrie Irving and Al Horford depart, and the team revamped its image thanks to the addition of Walker, Brown came into the 2019-20 season with a refreshed attitude — and a fresh hairdo. It was all part of his plan to have his best season yet.

“[Last season] was tough. I suffer from a lot of anxiety. When you have so much expectations, especially in a city like Boston where they want to win, if you’re not performing you start to lose your confidence and start to doubt yourself,” he said. “A part of me coming into this year was not dealing with that negativity. Like, saying ‘F— that.’ I said, ‘Cut my hair, cut my care.’ Letting go, stop caring what people think, and I reached a new pinnacle of happiness and peace.”

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This year, Brown has thrived in his bigger role, both in the offense and as a leader in the locker room. He relishes in that added responsibility as a leader, and he’s made it clear that it’s not just his paycheck that will continue to grow; so will his impact on the floor.