I think a more logical trade involves Pierce to Dallas, two out of Heywood/Odom/Marion being absorbed by Boston's cap space, and the Celtics getting compensated with Dominique Jones and Roddy Beaubois (plus a draft pick?), while Dallas maybe clears enough cap space to add Dwight Howard or Deron Williams.
Huh? Pierce and Dirk would eat enough of the cap combined to shoot the dreams of Deron/Howard down.
Pierce makes 16, Dirk makes around 20 right? That is enough to take them down to a single high level FA right there.
There are actually scenarios out there for Dallas signing both Dwight Howard and Deron Williams that work. They involve trading Odom and either Heywood or Marion and amnestying the one that isn't traded.
I'm just positing the scenario of the Mavs ending up with Howard/Pierce or Williams/Pierce instead of Howard/Williams. (Note the use of the word "or".)
I don't think they have to trade Odom, his deal is only partially guarenteed. They need to buy him out, trade one of Marion/Haywood, and then amnesty the other.
So why would they give up assets to get Pierce instead of just trading Marion/Haywood to open up the two max salary slots? I don't see them having any issues moving Haywood or Marion to another team under the cap.
Only if Howard and/or Deron is already off the market would they move for Pierce, then it makes sense.
The theory is that they would trade the partially guaranteed contracts of Lamar Odom and Vince Carter (still guaranteed for a combined $4.4m next season) to other teams, who would then probably waive them.
I could see Howard or D-Will being off the market. Howard could decide he values the extra $30m or whatever that only Orlando can give him. There are suspicions that Daryl Morey wants to sell high on Kyle Lowry and sign Williams (who grew up in Texas).
Jones and Beaubois are assets that the Mavs might be expected to give away to grease the wheels of a salary dump of Odom/Marion/Haywood. If, instead of clearing cap space to sign a superstar, they trade for a superstar already under contract, why not?