Some people are proposing trade ideas that revolve around a Glen Davis sign-and-trade. I find it a bit ridiculous to believe that any team covets Big Baby enough to want to do a sign-and-trade for his services (assuming sign-and-trades are even possible in the next CBA...another reason why I find all this armchair GM trade wankery so ridiculous).
Here are some suggestions I have seen:
BBD S&T to Charlotte for Tyrus Thomas ($7.3 million in 2011-2012)
BBD S&T and Jermaine O'Neal ($6.23 million) for Rip Hamilton ($12.5 million) and Ben Wallace ($2.25 million)
BBD S&T, Rondo ($10 million), and the Clippers pick for Steve Nash ($11.7 million), Marcin Gortat ($6.8 million), and a second round pick, with a third team somehow involved to help salaries match.
But even if Davis is somehow a widely coveted free agent, a sign-and-trade deal offers problems due to base year compensation rules.
As Larry Coon states in [urlhttp://members.cox.net/lmcoon/salarycap.htm#Q76]his NBA Salary Cap FAQ[/url]:
Base year compensation (BYC) prevents another salary cap loophole. Without BYC, a team over the salary cap that wants to trade a player, but can't because of the Traded Player exception (which says teams can't take back more than 125% of the salary they trade away), could just sign the player to a new contract that fits within the desired range, then do the trade. BYC says "if you re-sign a player and give him a big raise, then for a period of time his trade value will be lower than his actual salary."
Translation: Even though Boston has BBD's Bird rights, it can't just sign him to whatever amount makes a trade work.
In 2010-2011, Glen Davis made $3.3 million. A 20% raise would be to $3.96 million. In the summer of 2010, the MLE was $5.765 million. Let's say that, if the CBA continued the same way, it would be about $6 million, a nice, easy round number to work with. And a sign-and-trade usually involves a salary more than the MLE. If it didn't, a team that wanted Big Baby would just sign him using the exception. Most posters proposing trades seems to assume Davis would get at least that much.
So, we can assume that BBD would get a raise to at least $6 million in most S&T scenarios. If it is more than $3.96 million, BYC matters, and I have shown that it likely will. If his first-year salary is $6 million, then his base year compensation is $3.3 million (since it is more than half of $6 million). The Celtics would be able to bring back no more than $100k + 125% of $3.3 million, or $4.225 million in salary. If the other team sent out $4.225 million in salary, then it could bring back no more than $5.38 million in salary, which is less than the $6 million Davis would be pulling in. The more you pay Davis, the wider the gulf.
The way around this usually involves adding more players to the deal so that the difference between BYC and actual salary is a smaller percentage of the salaries involved or having a third team renting out its cap space or a traded player exception in exchange for compensation. Thus, a sign-and-trade involving Glen Davis is probably not a likely avenue for improvement in the off-season because of BYC. I was originally going to write this up as one reason why a S&T with Krstic (who would be more likely to sign a contract for an amount without BYC complications) was a better idea than a S&T with Davis, but Krstic has apparently scampered off to Russia.
These problems also exist if you give Jeff Green a big raise over the $4.46 million he received this past season in a sign-and-trade.
The bottom line is that, even if it wasn't silly to talk about sign-and-trades without knowing what is possible under the next CBA, this is probably not a method of improving the team due to base year compensations rules. It's not impossible, but it probably requires moving one (or more) of the Big Four, and I just don't see that happening. Either that or I am reading the rules wrong.