Two-time All-Star wing Jaylen Brown has agreed to a five-year, $304 million supermax contract extension with the Boston Celtics, making him the highest-paid player in NBA history, his agent, Jason Glushon of Glushon Sports Management, confirmed to Yahoo Sports. ESPN's Marc J. Spears first reported the deal.

The contract is fully guaranteed. There is no player option for the final year of Brown's deal in 2028-29. The contract includes a trade kicker that would increase Brown's salary even further if he is dealt at any point.

The 26-year-old averaged a career-high 26.6 points per game (49/34/77 shooting splits), 6.9 rebounds and 3.5 assists in 35.9 minutes a game this past season, helping Boston to Game 7 of the Eastern Conference finals. The Celtics have made the conference finals in five of Brown's seven seasons, including a trip to the NBA Finals in 2022, when they lost to the four-time champion Golden State Warriors in a six-game series.

The richest contract in league history is a matter of great timing on Brown's part. He was the only member of the 2016 draft class to earn All-NBA honors with a year remaining on his current deal, which qualified him for the supermax extension this summer. Brown will earn $28.5 million before his extension begins in 2024.

Brown was reluctant to discuss his future in Boston this past season, understandably upset after a season-ending loss to the Miami Heat and telling The Ringer's Logan Murdock earlier this year, "I don’t really know or want to answer that question because that type of stuff makes Celtics fans speculate and go crazy."

Still, turning down $304 million guaranteed when the alternative in 2024 could be $100 million less is a no-brainer. Celtics president of basketball operations Brad Stevens confirmed as much in a news conference at season's end, telling reporters, "I'm not allowed to talk about the contract details, let alone the extension ... but I can say without a doubt that we want Jaylen to be here. He's a big part of us."

Brown's teammate, Jayson Tatum, will become the league's highest-paid player next summer, when he becomes eligible for a supermax extension worth further north of $300 million. There is much debate about whether paying Brown in addition to Tatum is Boston's best path to a championship, especially in light of a new collective bargaining agreement that severely restricts high-priced teams from building out rosters.

Brown struggled at times in the playoffs, particularly as a playmaker and especially in this year's conference finals, where he shot 16.3% on six 3-point attempts per game and totaled more turnovers (25) than assists (24). Some of his production decline can be attributed to a laceration on his shooting hand that repeatedly reopened throughout the playoffs, but he also struggled to contain his ball-handling in the 2022 Finals loss.

Still, Brown turns 27 years old in October, and Tatum does not turn 26 until March. They have finished no worse than the conference finals every year they have both been healthy for the playoffs since 2020. (Brown missed the 2021 playoffs with a torn ligament in his left wrist, and the Celtics lost in the opening round.) They were four minutes and an all-time eruption from Stephen Curry — the greatest shooter in the history of the sport — away from taking a 3-1 lead in the Finals and all but guaranteeing themselves a championship.

It is not just possible that the Celtics could win with Tatum and Brown as their highest-paid players, it is proven. The alternative is shopping Brown for players who would almost certainly come no closer to a title. It is on Tatum and Brown to continue their upward trajectories into the prime years that still await them.

It is also on Boston's front office to build a more cohesive team around them. Stevens began that job as soon as the season ended in disappointment, smartly adding veteran assistants Sam Cassell and Charles Lee to rookie head coach Joe Mazzulla's staff and boldly trading 2022 Defensive Player of the Year Marcus Smart for 2018 All-Star Kristaps Porzingis and multiple draft picks, including rookie Jordan Walsh.

Before free agency even began, the Celtics boasted a deep rotation and BetMGM's best title odds in the East. It is pretty difficult to argue against paying Brown when he is bordering on the precipice at age 26.