Boston Celtics star Jaylen Brown is having a breakout year, and from Isaiah Thomas' observation, a notable change can be seen in Brown's confidence.

Sure enough, that change has translated into career-high numbers for the Celtics wing.

“I think it’s his confidence. Confidence is what takes you from being good to great, and he’s on the road to being that,” the Washington Wizards guard said of his former teammate, per Mark Murphy of Boston Herald.

In his fourth year in the league, Brown is putting up stellar numbers while donning the legendary green and white. He is averaging a career-high in points (20.6), rebounds (7.1) and assists (2.4) while shooting a ridiculous 52.1 percent from the field and 40.8 percent from the 3-point country.

His performance has garnered All-Star buzz. Some have even put him in the running for Most Improved Player. After all, last season was a tough campaign for the Georgia native, as he was given a bench role to make room for the ball-dominant Kyrie Irving.

While Brown tried his best to complement the star guard's playing style, his numbers plummeted and ultimately hampered his development.

So when the Celtics offered him a hefty four-year, $115 million extension, several raised their eyebrows and asked if Jaylen Brown was really worth the investment. But so far, Brown has met the expectations. It's very noticeable in his play, as he takes smarter shots, he's more in control, and more aggressive in trying to get to his spots.

More importantly, Brown is syncing seamlessly into Brad Stevens' system.

His efforts have aided the Celtics to a 25-9 record for second place in the East. Gone are the days when critics lambasted them for not maximizing their potentials. A lot can still happen in the 2019-20 season, but we all can say that the Celtics are back — much thanks to Brown's resurgence.