Does the NBA purposefully create all the exemptions and prohibitions and whatever to confuse reasonably casual basketball fans like me? The MLE, the TPE, Bird rights, whatever issue this is... I can't keep it all straight.
To follow 90% of NBA transactions, you don't need to be a lawyer (though I am so take this with a grain of salt). TPE rules are more arcane, but if you know your team has one - just think of as cap space that can be used in a trade.
If you're a casual fan, you need to know that:
1. The league has a soft salary cap;
2. The league has a luxury tax. The level at which a team pays the tax is around 25M more than the cap. Exceeding the tax for multiple years increases the amount of tax payments. The amount paid by the taxpaying teams is distributed to the non-tax paying teams.
3. To sign a player to a new contract you need either space under the salary cap or use an exception.
4. The exceptions that matter the most are:
Bird rights - basically the ability to exceed the cap for a guy who is already on your team. Easy to understand why this exists.
The midlevel exception - each team gets one each year. Tax paying teams get a smaller one than non-taxpaying teams. It is basically the ability to sign a middle class player each year even if your team is already over the cap.
5. The CBA limits the amount of years and dollars in a contract. An incumbent team can offer a free agent more in years and dollars, than a new team.
6. Teams that want to trade players either they need to: Match salaries on both sides of the transaction OR the team acquiring players has cap space or a TPE.
While a little complicated, I think the NBA's cap rules make intuitive sense most of the time. They are all about incentivizing (allowing small markets to keep homegrown talent - Bird Rights, max salaries, Restricted Free Agency) or dis-incentivizing (large market teams using the exceptions to the soft cap to massively out spend smaller market teams- Luxury Tax, max contracts) certain behavior.
In contrast, I feel like the NFL's cap rules are completely opaque.