It appears the lee for Bayless trade was done via trade exceptions.
If that's the case then we now have two exceptions.
1) the pierce exception now looks like it is $7,140,136. This is Bayless salary subtracted from the original pierce TE.
2) the lee exception is now $5,225,000.
The lee exception can now be used until the beginning of 2015.
So this is the impression I got too (they send us Bayless for an exception and we send them Lee), but I haven't seen it confirmed anywhere.
Also how can we do two deals like this that are clearly linked, while the NBA didn't allow us to do two deals that were linked with the CLippers in the off season?
It's a weird NBA rule. You can have simultaneous trades. And you can have trades that are applied differently for each team. So from the Celtics perspective, they had two choices: They could trade Lee for Bayless straight up, and acquire a ~$2.1 million exception, or they could trade for Bayless using a portion of their Pierce exception, leaving it at around $7 million, and trade Lee to Memphis and acquire a new exception at his salaray of $5.2 million. The NBA will allow them to do either, no matter that Memphis is using a trade exception to acquire Lee.
My assumption is that the Celtics would preserve their exception from Pierce and gain a smaller exception for the difference Lee and Bayless' salaries, because having a larger exception is better since they can't be combined. However, the Lee exception will expire roughly 6 months after the Pierce exception, so there is some argument to preserving flexibility for an in-season trade next year.