This plan is based upon the idea that there is legitimate interest from the Lakers in acquiring Rondo. It also assumes that Dallas is desperate to clear cap space to sign Dwight Howard (and possibly also Deron Williams), who has politely told the Celtics he does not intend to go to Boston. Also, Brandon Bass opts out because another team is willing to hand him a long contract for $7 million/year. All salary cap data is taken from shamsports.com. The trades may need tweaking, but I don't think it is completely ridiculous as a first draft and I think it illustrates how cap space has more use than just signing free agents.
Step one. The Celtics renounce everyone and cut the unguaranteed contract of E'Twuan Moore.
Step two. The Celtic acquire Paul Gasol for Rajon Rondo, a 2012 first round pick, and a lottery-protected future first round pick. The Lakers also pick up a trade exception of $8 million. The Lakers could make the trade exception $762,195 larger by sending Andrew Goudelock to the Celtics, who would then waive Goudelock and his unguaranteed contract. By my calculation, that would be required if the Lakers wanted to get Shawn Marion from Dallas. One option is that the Lakers could accept Brandon Bass (if he doesn't opt out, or in a sign-and-trade if he does) and a smaller trade exception.
Step three. The Celtics help the Mavericks create cap space by taking on the contract of Brendan Haywood. The fee to do so is that the Celtics get Rodrique Beaubois. In return, Dallas gets some sort of future draft consideration. The Mavs got a future second round pick for Rudy Fernandez and Corey Brewer. Given the ridiculously long contract Haywood has (signed through 2015-2016, with the final season completely unguaranteed), arguably the Mavs shouldn't ask for much if they can avoid having to amnesty Haywood's huge contract in order to sign Dwight Howard.
That leaves the Celtics with a team of Roddy Beaubois and Avery Bradley manning the point, Paul Pierce at small forward, Paul Gasol at power forward, at Brendan Haywood at center, and JuJuan Johnson on the bench.
Including $1 million for the Celtics' remaining first round pick and a $500K roster charge for each roster spot under 12 men, that puts the Celtics' salary figure at around $52.6 million. Let's assume the salary cap is around $61 million, which is an estimate I have seen in several places. That gives the Celtics $8.4 million to play around with in cap space, but keep in mind that you can include the approximately $500K roster charge to what you pay guys as you fill the first twelve slots on the roster.
Step four. Kevin Garnett and Ray Allen want to come back for reduced salaries. You can take the extra cap space and give them contracts along the lines of $4.7 million with a player option for a second year for a similar amount. They can agree to take less to allow the Celtics to sign another free agent, of course.
That leaves the "room" exception, which can be for two years at $2.5 million, given to teams with cap space who have to renounce the full-sized MLE in order to sign free agents. My dream is that Pietrus likes Boston and agrees to sign for this amount.
That gives Boston a team of:
Gasol, Haywood, and Garnett at power forward and center. JaJuan Johnson is the fourth big off the bench. Paul Pierce, Ray Allen, and Mickael Pietrus form a three-man rotation at the wings. Roddy Beaubois and Avery Bradley form an offense-defense combo at point guard. The Celtics also have a first- and second-round pick on the roster.
Step five. Fill out the bench. These moves give a roster of 11 so far. I would be happy with bringing back Sasha Pavlovic and Greg Stiemsma on minimum contracts, favoring continuity and bringing back players who have familiarity with the team's system. That leaves two spots. I would be happy to fill those two slots with the best D-League players who fit into Doc's system. If available, I wouldn't mind the Celtics taking a flyer on players such as Blake Ahern or Manny Harris. And there's always the possibility that another player of the quality of Pietrus will be available. I also would not be averse to Jermaine O'Neal coming back as a minimum salary guy expected to play no more than 10-15 minutes per game when healthy (sort of like Jeff Foster in Indiana). A veteran third-string point guard who can handle a string of DNPs might also be something worth looking for.
I have one other idea for finessing the salary cap. I'm not entirely sure it works, but I think it does. Before the last game of the season, cut the 15th man on the roster and sign Jeff Green to a minimum contract if he seems to be recovering well. As a Bird rights free agent, his cap hold will be 150% of his previous salary, which would be the minimum. If I did the math right, in my dream scenario, this would require KG and Ray Allen to agree to salaries of around $4 million to accommodate the cap hold for Jeff Green, who can then be signed for more than the minimum.
A theoretical roster might look something like:
Bigs - Pau Gasol, Kevin Garnett, Brendan Haywood, JuJuan Johnson, Greg Stiemsma
Wings - Paul Pierce, Ray Allen, Michael Pietrus, Jeff Green, Sasha Pavlovic
Point guards - Rodrigue Beaubois, Avery Bradley, veteran minimum salary third-string point guard
Unknown position - first round pick, second round pick