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The Boston Celtics agreed to a four-year, $115 million contract extension with forward Jaylen Brown on Monday.  

Jason Glushon, Brown's agent, informed ESPN's Adrian Wojnarowski about the terms of the agreement. Yahoo Sports' Chris Haynes reported more contract details: "He can secure $8M in incentives if he wins MVP, DPOY or makes one of three All-NBA Teams. He pockets $4M if plays 65 or more games, team wins 49 or more games and reaches second round of playoffs. Total guaranteed salary $103M."

Brown, 22, was the No. 3 overall pick in the 2016 draft. He averaged 13.0 points and 4.2 rebounds on 46.5 percent shooting last season, disappointing those who expected him to have a big year in the wake of his breakout during the 2018 playoffs.

While Brown could become a two-way star in due time, he remains a developing player on a team that is looking to make a title push.

The Celtics have lauded Brown's improvement on defense in particular.

"He definitely has a lot on him. We know, and this coaching staff knows, his ability," Celtics guard Marcus Smart said about Brown in December 2017, per Chris Forsberg of ESPN. "And [Brown is] athletic enough to guard a lot of guys. So once he understands that and he takes that head-on, he'll be a better all-around player. And he's been doing a pretty good job so far."

According to Chris Haynes of Yahoo Sports, the Celtics initially offered Brown a four-year, $80 million extension, which he turned down. Negotiations continued up until the Oct. 21 deadline for rookie extensions, and the two sides came to a middle ground. 

Brown isn't good enough to be considered a cornerstone of the Celtics, but he's still young and has flashed a ton of potential at times. He doesn't turn 23 until later this month, and his year-to-year improvement suggests an even bigger ceiling could be on the horizon.