Jayson Tatum's historic extension limits Celtics roster flexibility

With rules agreed to in the 2023 collective bargaining agreement (CBA) going into effect, those massive deals will soon hinder Boston's ability to add more players to its championship core.

ESPN's Tim Bontemps and Bobby Marks wrote an article explaining that the CBA's most significant change "is the addition of the first and second 'aprons' above the luxury tax line, both of which cut heavily into teams' flexibility when building out rosters."

As detailed by Yahoo Sports' Jake Fischer, teams above the second apron — such as the Celtics — face multiple constraints. Those include trade restrictions, such as the inability to match salaries in a trade by combining two players' contracts and eliminating the use of the mid-level exception (MLE).

A freeze is also placed on a team's first-round pick seven years into the future, which Fischer noted is a valuable asset for contenders to dangle in trades.

Boston, however, has set itself up for a multiyear stretch with its championship core. Earlier on Monday, the team agreed to a four-year extension with guard Derrick White. And back in April, Jrue Holiday signed a four-year extension of his own, keeping both defensive standouts under contract through 2028.  

With Brown on the books through 2029, Kristaps Porzingis (2026) is the team's only top-five player set to become a free agent in the next three years.

If something were to go awry, however, the Celtics would have limited means of pivoting. And they'll be paying heavily for their extended championship-contending window.

Per Spotrac, the Celtics already have $210.3M in active cap for the 2025-26 season. According to ESPN, they could own an astronomical $450M combined in salaries and luxury tax costs.

That's only accounting for eight players, too.

"The NBA is not telling front offices that they have to break up their teams... What they are saying is there are not only financial consequences but also severe restrictions in how you can add outside of your own players," a team executive said in the Bontemps and Marks article.

"I'm not anti-dynasty, but you want dynasties to be created, to the extent possible, with a level playing field," commissioner Adam Silver said in April, per ESPN.

The Celtics made the no-brainer decision to extend Tatum, but it will ultimately be judged alongside the team's results from the next four years.