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Jaylen Brown has agreed to a five-year, $304 million supermax extension with the Boston Celtics, according to Shams Charania. The deal -- the richest in league history -- will be fully guaranteed and include a trade kicker, but the final year will not include a player option, according to Charania. Brown, whose last contract was below both his max and his market value, became eligible for a supermax extension once he earned All-NBA honors this season.

However, it took time for the two sides to agree to the specifics of a deal. Brown was eligible for this contract on July 1, but it seems as though the two sides spent most of July negotiating the bells and whistles on the deal. In the end, both sides managed to get meaningful concessions. Brown got a fully guaranteed deal with a trade kicker should he ever be moved. Boston got an extra year of team control by denying him a player-option in the final year of the deal.

The deal, at this moment, is the most expensive contract in NBA history. Based on the assumed 10% growth in the salary cap (the maximum allowable within the CBA), it will pay Brown a total of $303,734,891 with an average of $60,746,978.20 per year. Here's how the salaries are expected to break down per year, without including a possible trade kicker:












Brown may have the most expensive contract in NBA history for now, but that status never lasts long. With a new TV deal looming and revenue at an all-time high, the cap is expected to jump 10% annually for the foreseeable future. Max contracts are tied to the cap, with the highest starting salary possible for most players being 35% of the cap. Brown's teammate, Jayson Tatum, will be eligible for a similar contract next offseason that will eclipse this one. 

With Kristaps Porzingis on the books for roughly $30 million per year and Derrick White and Robert Williams III also combining to make around that much, Boston will have one of the NBA's most expensive rosters for several years to come. With the NBA's new second apron rules in place, that will severely limit Boston's flexibility in building a roster around its existing core.

But the Celtics have already reached the NBA Finals with Brown and Tatum and nearly did so again last season. The Porzingis addition adds a new dimension to their offense, and both White and Williams still have room to grow as relatively young players. 

Boston is paying quite a bit for its roster, but based on recent results, it would be hard to argue that it isn't worth it. Tatum and Brown have turned the Celtics into consistent title contenders. Now that Brown has extended, they should remain there for years to come.