On Thursday, the floodgates will finally open on the NBA’s bold new future when the free agent period finally opens for business. 

Several franchises have planned and schemed for years, throwing seasons away at the mere prospect of adding LeBron James or Dwyane Wade. They have made questionable basketball decisions and seemingly lopsided trades with the inevitable goal of cap space serving as a more valuable asset than living, breathing players. 

For the Knicks, Heat, Bulls and Nets, Thursday is the day that begins a new direction for their teams, to say nothing of the Cavaliers and Raptors who may be scrambling to replace their franchise players.

All the focus is on LeBron, D-Wade and Chris Bosh, and to a lesser extent, Amar’e Stoudemire, Carlos Boozer, David Lee, Joe Johnson and Rudy Gay. Dirk Nowitzki added himself to the mix by opting out of his deal with the Mavericks as did Paul Pierce late Tuesday night. 

With the exception of re-signing Pierce, the Celtics are not in the market for those players. They have a direction and Danny Ainge has spelled out his intentions several times. He wants to bring the team back to continue its run and that means re-signing Pierce and Ray Allen and returning Doc Rivers to the bench. 

What the Celtics do not have is cap room, at least not yet. In theory, Ainge could renounce the ‘Bird rights’ to Pierce and Allen, as well as the other six free agents to create about $10 million in cap space. They would also lose the ability to go over the cap to re-sign them and they would lose the Mid-level exception, which will translate into a little less than $6 million once the cap is set on July 7. 

For now, they also have Rasheed Wallace’s contract against the cap. Wallace has not officially retired and we won’t know more about his situation until he files the paperwork and he and his agent talks with the team. They could come to a buyout agreement or Wallace could simply walk away. Until that happens, he remains on the payroll and on the cap.   

The odds of all that happening are remote, which is why bringing everyone back and retooling the team in the short term is the best option available to Ainge.  

This is also by far the most realistic scenario. Having cap space is one thing. Using it to build a team is another. Just ask the Knicks, who are sitting on a pile of cap space and a dwindling set of options if they swing and miss on LeBron, which seems increasingly likely.

Pierce’s decision to terminate his contract makes things more difficult for Ainge, but if he is able to follow through on his plan, he will still have holes to fill, primarily in the back line where Kendrick Perkins is facing offseason knee surgery and rehabilitation. Perkins told reporters Tuesday that he will have surgery next week and could be out until December or January. 

This is where Ainge will likely focus the money available in the Mid-level exception. The important thing to remember about the MLE is that it can either be broken up and used on several players or it can all go to one. 

In the summer of 2007, Ainge used Mid-level money to sign James Posey and Eddie House. In 2009, all of it went to Wallace. (Another note: If the Celtics were to somehow get under the cap, they would lose the Mid-level exception. The key word there is “exception.”) 

Here’s a look at the realistic options for the Celtics in free agency starting with the big men, which is the highest area of need. 

BIG MEN

Signed: Kevin Garnett, Kendrick Perkins, Glen Davis, Rasheed Wallace (until he officially retires)

FA: Shelden Williams

Others: Semih Erden

Analysis: Erden is a 24-year-old 7-footer from Turkey. The Celtics have his rights and Ainge has indicated that the time may be right for him to come to the states. Erden is obviously a bit of an unknown, but he could bump Williams from a roster spot. 

Perkins and Davis are both in the last year of their contracts and Davis is no longer a base-year compensation player, which would make them attractive trade chips if Ainge goes that route. 

The Celtics need size more than anything and a player who is capable of stepping into the starting lineup until Perkins is able to return.  

MID-LEVEL OR CLOSE

Once Bosh, Stoudemire, Boozer and Lee are off the board, the market for the following players will likely start at the MLE. 

Brad Miller: Miller’s name has already been linked to the Celtics and it makes sense. Miller is a tough, physical player who is also skilled offensively. He is a good passer and until last season, he was also an excellent shooter. 

Therein lies the reason for concern. Miller’s numbers dropped across the board and in many ways his fall resembled Wallace’s final season in Detroit. He also took far more 3-pointers than he has in the past. 

Miller is 34 years old and it’s fair to ask if that was a bad season on a disjointed Bulls team or a sign that the end of his career is in sight. Even with those caveats, there will be competition for his services. The Rockets have already mentioned as a suitor and in such a top-heavy market he will be one of the few notables left standing once the dust settles. 

Jermaine O’Neal: Yes, the Celtics made O’Neal look terrible in the playoffs but he had a bounce-back season in 2009-10 and seems to be adjusting to a reduced role. He’s also younger than Miller, although he has played more NBA games and has some injury risk. 

Assuming Perkins is able to come back, O’Neal would have to get used to a reserve role, but there’s no reason why he can’t continue have a few more productive seasons in that capacity. 

Brandan Haywood: This is probably a longshot as Haywood stands to benefit from all that remaining cap space by securing a larger deal than the Mid-level. 

Haywood has very quietly turned into an above-average starting center in the NBA, but if he is available at that rate, he is the best, and youngest, option of the bunch. 

LESS THAN MID-LEVEL

If the Celtics can’t get a starting-caliber center, there are a number of more affordable veteran options available that would also allow them to use some of the exception money to fill other roster holes. 

Kurt Thomas: Thomas will be 38 years old when the 2010-11 season starts and he is long past the point of being an effective starter in the NBA. 

However, Thomas brings toughness, intelligence and a hint of rugged crazy that would play well with the Celtics. In limited minutes his rebound numbers have stayed fairly consistent and while his shooting has slipped, he can still knock down a mid-range jumper, which would also fit with the Celtics. 

Ben Wallace: Remember him? Wallace returned to Detroit last season and piled up rebounds at a consistent level. Wallace was particularly good on the offensive glass where he had one of the highest rebounding rates in the league. 

Like all of the centers on this list, the big question is how much does he have left? 

WILD CARDS

Shaquille O’Neal: The fit would be less than ideal, but stranger things have happened. 

Zydrunas Ilgauskus: It’s hard to see him playing anywhere other than Cleveland and he can’t get up and down the court all that well anymore, but he can still stick a long-range jump shot. 

Tyson Chandler: Chandler can terminate his contract and there are rumblings that he might do that even though it’s hard to see him getting more than the $13 million he would be leaving on the table. On the other hand, if he does opt out he’d likely get more than the Celtics have to give. Still worth a phone call if it happens. 

WINGS

Signed: None

FA: Paul Pierce, Ray Allen, Tony Allen, Marquis Daniels, Brian Scalabrine, Michael Finley

Others: Tony Gaffney (non-guaranteed), Luke Harangody (second round pick)

Analysis: This isn’t as barren as it looks assuming Ainge can work out deals for Pierce, Ray Allen and Tony Allen. Daniels, Scalabrine and Finley are less likely to return. 

MID-LEVEL OR CLOSE

The big names here are LeBron James, Dwyane Wade, Joe Johnson and Rudy Gay. It’s possible the Celtics won’t have the money to offer the bigger names in the next tier if they use their resources on a center. 

Mike Miller: A fantastic shooter who stopped shooting the last two seasons for reasons no one can adequately explain. Perhaps it was playing on bad teams like the Timberwolves and Wizards, but Miller’s shot attempts dropped from 12 a game in 2008 to around eight per game the last two seasons. 

If they find the money to pay him, Miller would be a huge asset to the bench that has been starved for outside shooting since Posey and House left. He would also serve as valuable insurance for Allen and Pierce. 

Josh Howard: Reports out of Washington are that the Wizards won’t pick up the option on Howard’s contract, which make him one of the more intriguing free agents on the market. Howard was an All-Star in 2007, but injuries have taken a toll and his production has fallen accordingly. 

Given the uncertainty and injury problems, he’s probably too big of a risk for the Celtics. 

Ryan Gomes: The former Celtic was waived by the Blazers in a cost-cutting move, but he can still play and he remains a fan favorite. His versatility would also be an asset and he could add some scoring punch to a second unit that needs it.  

Matt Barnes: Barnes morphed from a gritty overachiever into a slightly-crazy overachiever with the Magic. He’ll play defense, knock down shots and drive opponents insane, but he’ll probably command more money than the Celtics would be willing to spend for those skills. 

Raja Bell: He’s a few years removed from his glory days as a Kobe stopper in Phoenix, but Bell could be an attractive option if Tony Allen goes elsewhere. 

OTHERS

Travis Outlaw is a 6-foot-9, 3-point specialist who doesn’t rebound. Hakim Warrick is a 6-foot-9 rebounder who doesn’t shoot 3-pointers. Combine the two and you would get a good player. Individually, they could be interesting if they fall through the cracks. 

Then there’s Tracy McGrady who may be worth taking a flyer on for the right price. 

POINT GUARDS

Signed: Rajon Rondo

FA: Nate Robinson

Others: Avery Bradley, Oliver Lafayette (non-guaranteed)

Analysis: The Celtics are in good shape with Rondo signed for the next five seasons. They have operated without a true backup point guard for three seasons, which has never seemed to bother Ainge all that much. 

If Robinson decides to return and is ready to play the role he filled in the playoffs, then the position is settled. But he’ll get offers from elsewhere and it remains to be seen if he would be willing to accept that role at this point in his career. 

Bradley could also fill that role, but as Ainge cautioned on draft night, he’s still young and he isn’t a natural point guard. Lafayette is a mystery until he gets a chance to show what he can do in summer league. 

This is the least pressing area of need for the Celtics, and they would probably be looking at bringing someone in for the veteran minimum. 

The options here include Steve Blake, a trusted veteran who doesn’t turn the ball over and makes 3-pointers. Eddie House had a great run for the Celtics and is still well-respected in the locker room, but he may be looking for more than the minimum.