Wyc Grousbeck says "trade season is not over yet" and he's right, because a trade is really the only way the Boston Celtics will be able to make a significant move during the free agent period, which begins on July 1st. That's because they will likely be over the cap, restricting them to only their exceptions for free agent signings.

Before jumping into Boston's salary cap situation, it's important to understand a few basic terms in regards to the salary cap for the first part of our Offseason Preview Series:

Projected Cap

The projected salary cap is set at $63.2 million and the tax level at $77 million, according to Larry Coon. However, those numbers won't be official until after the July Moratorium is over on July 10th.

Cap Hold

The NBA uses "cap holds" as placeholders for players the team is expected to sign, like pending free agents and draft picks. In other words, the Celtics have a cap hold on Marcus Smart valued at $2.7 million, and they have another for Kris Humphries, since they own his "Bird rights."

Exceptions

Another type of cap hold is an "exception," which includes the mid-level, bi-annual, and any other exceptions the team owns such as bird rights or trade exceptions. This year's mid-level exception is valued at $5.305 million, so the Celtics have a cap hold for that value. But they also have a trade exception valued at roughly $10.3 million, so that also counts when calculating Boston's salary cap space. They also own Bird rights on a number of free agents, which they can use to exceed the cap in order to re-sign their own players.

"Above" or "Below" the Cap

To be clear, a team is able to use the exceptions they possess if they are above the cap, but they are only able to use the amount of salary cap space they have if they are below the cap. Of course, all salaries and cap holds are included when determining the cap space below the cap.

Do the Celtics have cap space?

Yes and no. Once again, Boston will probably not have any cap room at all, meaning they will be restricted to using their "exceptions" to outright sign (or trade for) players.

The Celtics have $131.5 million dedicated to their team salary, cap holds, and exceptions. This means that they would have to "renounce" all of these figures in order to clear as much cap as possible, giving them some space.

But this is not necessarily a bad thing; in fact, being above the cap gives them more wiggle room to sign players by utilizing their exceptions, the mid-level or bi-annual, and then their three trade exceptions.

Why is that? If Boston renounced all of their cap holds (Pierce trade exception, pending free agent Bird rights, etc.) and declined player options (Bogans, Pressey, etc.), the most cap space they'd be able to open up is $9.5 million, with a total salary of $53.7 million.

Even if Boston went ahead and used the stretch provision on Gerald Wallace (which would not be a wise move in this scenario), they would still only have $15.1 million available in cap room.

On the other hand, as it currently stands, they have $27.9 million available in the form of trade, mid-level, and bi-annual exceptions, and in the form of non-guaranteed contracts. This makes the Celtics' situation heading into the summer very unique, since they are one of the few teams able to trade "dead money" by using the trade exceptions and non-guaranteed contracts.

But remember, despite that hefty total, the Celtics would still have to stay under the projected tax line of $77 million if they wanted to avoid paying luxury tax and the projected hard cap of $81 million.

How can the Celtics acquire players?

Even though Boston will likely be over the cap, they still can acquire players through free agency or trades by using their exceptions. Here are a few examples:

Bird Rights

Kris Humphries and Jerryd Bayless are both pending unrestricted free agents, but the Celtics can re-sign them by using their Bird rights, which are exceptions that can be used by teams on their own pending free agents in order to exceed the salary cap, up to the player's maximum allowed salary.

In other words, if the Celtics want to re-sign Humphries, they can freely do so without worrying about using other exceptions or by clearing cap room, like they would if they tried to sign other unrestricted free agents.

Mid-Level and Bi-Annual Exception

If there is a player from another team the Celtics wish to sign in free agency, they have the mid-level and bi-annual exceptions to use. Here's an example: If the Celtics want to sign Patty Mills, they will have no available "cap space" to do so, but they can use either of their exceptions to get it done. So, Boston could offer Mills a total contract of four-years and $12 million. Even though they'd be "above the cap," the mid-level and bi-annual exceptions are there to allow teams to still sign players.

Sign-and-Trade

Boston is in a good position to react to opportunities that may arise since they have so many non-guaranteed contracts and trade exceptions to use in deals with other teams. If they want to acquire a player who will likely make more than what they can offer ($5.305 million using the Mid-Level exception), then the only way they can acquire that player is through a sign-and-trade.

For example, if the Celtics want to make a run at a player who signed to a contract with a first year value of $10 million, one way they'd be able to acquire him in a deal is with a sign-and-trade. In this case, Boston could comfortably use its $10.3 million trade exception to absorb the contract in a deal.

Or even in a smaller deal, for a player with a contract valued at $6 million, the Celtics could acquire that player in a deal for the non-guaranteed contracts of Keith Bogans ($5.3 mil) and Chris Babb (816k) to make it work.

What can we except from Boston this summer?

This is a difficult question to answer because the Celtics have a lot of options and assets at their disposal, but it takes two to dance. To put it simply, there are too many variables to considering: Can the Celtics find a team willing to do a sign-and-trade? Would that player even be willing to come to Boston? Are the realistic and acquirable players even worth giving up valuable assets for? Can any true impact players be acquired with just the Mid-Level exception?

But what we can expect is that the Celtics will do everything they can to improve the roster. With the lack of a rim protector and go-to scorer, they will probably look to add talent that can possibly fill those roles. However, it's easier said than done, and there are no guarantees they'll be able to accomplish those goals this summer.

Yet, with so many movable assets, it's almost a guarantee that the 2014-15 Boston Celtics will look a lot different than they did in 2013-14; but it's an unknown if that translates into more wins next season.

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