For the past 15-plus years, Big Threes have dominated the NBA. From the Boston Celtics to the Miami Heatles and the Golden State Warriors, star-laden trios have routinely guided their teams to championships, leaving many of their contemporaries as footnotes in league history.

The NBA's latest collective bargaining agreement could change that. A handful of new rules will make it increasingly difficult to build around three stars if they're all on maximum or near-max contracts.

The biggest change was the introduction of a second salary-cap apron, which was set $17.5 million above the luxury-tax line in 2023-24. (It will increase at the same rate as the cap annually.) Teams that exceed the second apron become subject to punishing restrictions that will make it difficult for them to meaningfully reshape their rosters.

That wasn't the only change that might affect team-building. The new CBA changed its luxury-tax system to reduce the tax rate for the first two brackets (roughly $10 million over the tax line), but it increases relative to the previous CBA from there. Warriors governor Joe Lacob is already on record as being mindful of the new tax rates, particularly for those subject to the repeater tax.

For those who want a refresher on the new rules before the start of the offseason frenzy, we've got you covered.

The First Apron

Teams above the first apron (projected to be $178.7 million in 2024-25):

• Can't use the non-taxpayer mid-level exception or bi-annual exception
• Can't take back more salary in a trade than they send out
  
• Can't acquire a player via sign-and-trade
  
• Can't sign a player from the buyout market who was earning more than the non-taxpayer mid-level exception ($12.9 million) before getting waived
  
• Can't use preexisting trade exceptions
  

The previous CBA had only one apron. Teams that crossed it lost access to the non-taxpayer MLE and bi-annual exception, couldn't sign-and-trade for players and were subject to increasingly steep luxury-tax rates, but those were the only major restrictions.

The two big additions are the salary-matching and buyout market rules. Had they been in place over the past few seasons, the Los Angeles Clippers couldn't have signed Russell Westbrook after the 2023 trade deadline since he was coming off a $47.1 million salary.

With that said, there aren't a ton of impact buyout players every year. The salary-matching rule is a far bigger deal, as teams previously were allowed to take back 125 percent of the salary they sent out in a trade, plus $100,000. Now, they can't take back a cent more than they send out.

Based on the current reported structure of the Mikal Bridges trade, the New York Knicks will be hard-capped at the first apron since they're taking back more salary (Bridges) than they're sending out (Bojan Bogdanović and a mountain of future first-round picks). They still managed to re-sign OG Anunoby despite that restriction, but it might come at the cost of losing Isaiah Hartenstein in free agency.

The Second Apron

Teams that go above the second apron (projected to be $189.5 million) face all of the same restrictions as first-apron teams, along with the following:

• No access to any mid-level exception in free agency
• Can't aggregate contracts in trades
  
• Can't send cash in trades
  
• Can't acquire players when they sign-and-trade their own free agents elsewhere
  
• Can't trade a first-round pick seven years in the future, and that pick falls to the bottom of the first round if a team is over the second apron at least twice in a four-season span
  

The second apron didn't exist in the previous CBA. This is a new way to prevent teams from running up their payrolls in the pursuit of titles.

The aggregation restriction is the biggest change, so let's start there. Teams over the second apron cannot combine salaries to acquire a bigger contract. They can only take back equal or less salary for any player they send out in a trade.

Had those rules been in place last offseason, the Boston Celtics couldn't have acquired either Kristaps Porziņģis or Jrue Holiday. The Phoenix Suns also wouldn't have been allowed to trade for Bradley Beal. (In retrospect, the Suns might have preferred that.)

Second-apron teams also don't have access to any mid-level exception in free agency. They're allowed to re-sign their own free agents via whatever level of Bird rights they have on each one, but they can offer only minimum-salary contracts to free agents from other teams.

The Suns were the first major guinea pig in that regard last offseason. The varying success they had with their bevy of minimum signings casts doubt on the viability of top-heavy teams being built from scratch.

The New Tax System

For teams that aren't subject to the repeater tax, the new CBA reduced the penalty for teams that are $10 million or less over the luxury-tax line. However, the rate begins to spike significantly from there. It gets up to $4.75 per dollar spent for teams roughly $15-20 million over the tax line, which will likely discourage teams from going $30-plus million into the tax.

It's even worse for teams that are subject to the repeater tax, aka those that were taxpayers in at least three of the previous four seasons. The rates for those teams are slightly higher until they're $10 million over the tax line, at which point they spike considerably.

Repeater teams that are roughly $15-20 million above the tax line pay an outrageous $6.75 per dollar spent. That means a veteran-minimum signing would cost a projected $14.1 million in tax alone in 2024-25.

In mid-February, Golden State Warriors governor Joe Lacob told Tim Kawakami of The Athletic that he wanted the team to dip below the tax line in at least two of the next four years to escape from the repeater tax.

"It's just so prohibitive," he said. "Not to say we wouldn't do it if we had to, but you've gotta look at what the downside is to doing that."

The Warriors have racked up nine-figure tax bills in each of the last three seasons. The new CBA appears to have scared them off from continuing to spend at such a high level, though.

Salary Floor Changes

The aprons and the tax system aren't the only things that changed in the new CBA. The league's salary-floor rules are different, too.

Under the previous CBA, teams had to hit the salary floor—90 percent of the salary cap each year—by the final day of the regular season. Those that didn't had to distribute the shortfall to their roster, but that was the only real penalty that they faced.

As a result, a handful of rebuilding teams tended to largely forgo free agency in favor of carrying significant cap space into the season. They preferred to use their cap space at the trade deadline to absorb unwanted contracts from other teams for draft picks and/or young players.

The rules are far different under the new CBA. Teams now must hit the salary floor by the first day of the regular season. Any team that doesn't not only has to distribute the shortfall to its roster, but it also forfeits its (typically eight-figure) share of the luxury-tax disbursement. Those teams also get a phantom cap hold placed on their books to bring them up to the salary floor.

In other words, teams can no longer hoard $20-plus million of cap space until the trade deadline anymore. They'll have to be above 90 percent of the cap on the first day of the regular season one way or another.

More Extend-And-Trades Coming?

To the "This CBA sucks for the players!" crowd:

For one, talk to B/R's Eric Pincus.

Players didn't totally get the short end of the stick. For one, they got extension limits raised from 120 percent of a player's previous salary to 140 percent. That adds up quickly.

Extend-and-trades also got expanded limits.

Under the previous CBA, extensions signed in conjunction with a trade could be no more than three years in total, including years left on the current contract. They could start no higher than 105 percent of the player's previous salary with 5 percent annual raises. If a player waited six months after the trade to sign an extension, they'd be eligible for up to five years, 120 percent of their previous salary and 8 percent annual raises.

The new CBA now allows teams to offer four total years in extend-and-trades beginning at 120 percent of a player's previous salary. They're still limited to 5 percent annual raises unless the player waits six months to sign an extension, but that's a major upgrade over three years and 105 percent of the previous salary.

That rule change is what makes an opt-in-and-trade such a viable option for Los Angeles Clippers forward Paul George.

Under the previous rules, he'd be limited to a two-year extension via an extend-and-trade, and the Clippers are already offering him a three-year deal. Thanks to the new CBA, he can sign a three-year extension via extend-and-trade, and the 120 percent rule means it can begin at his maximum salary in 2025-26 (projected to be $54.3 million).