Isaiah Thomas witnessed firsthand the development of former No. 3 overall pick Jaylen Brown during Brown’s rookie year, when the two played together. Brown was joined by another third-round pick, Jayson Tatum, after Thomas left in the summer of 2017. Thomas claims that despite skepticism over the pair’s compatibility due to Brown and Tatum’s shared roles, they have proven their naysayers incorrect.

On Monday night, before Game 4 of the Eastern Conference semifinals against the Cleveland Cavaliers, Thomas remarked of Brown, “I’m very impressed, I’m not surprised at all though” during NBC Sports Boston’s Celtics Pregame Live. “[Brown] came in with an attitude that he was the best on the team — it was in a good way, though.”

After being chosen to a playoff-caliber club, Brown patiently waited for his opportunity to shine during his first year, according to Thomas. Thomas also gave Brown props for making the most of his chance and growing in his position year after year. Brown had a huge improvement from his rookie year, when he averaged 6.6 ppg, to his sophomore year, when he increased his average to 14.5 ppg. He began scoring more than 20 points a game in his fourth year and hasn’t stopped since.

Adding, “I’m a big fan of JB,” Thomas continued. Every day, he works harder to improve his game and remain one of the top players in the world. I know this because I’ve watched him play. It’s no wonder he’s where he is; in fact, I couldn’t be happier for his development, maturity, and playoff experience.

This season, Brown worked on improving his left hand. Last year, Brown made it a point to work on his left hand after receiving criticism regarding his turnover rate. Brown has managed to reduce his turnovers from 2.9 per game last season to 2.4 per game this season. He does this by effectively finishing with his left hand at the rim, confidently performing complicated dribble moves with his off hand, and even making a statement in the dunk contest.

“Obviously Jayson Tatum is just one of the best players in the world as well,” stated Thomas. “To see these two guys mesh so well together when a lot of people didn’t think they could play well together — they’ve proved a lot of people wrong, they’ve grown in every aspect of the game, and those guys are by far the leaders of the team.”