My guess would be that the leak is more likely to be coming from the Dallas end of the deal than Boston, with the goal to try to pressure Ainge into thinking that he's not going to have a better offer come along by getting the media, who seem to all think Rondo should be traded, to be a Greek chorus saying that Ainge has to agree. I also think Ainge is the sort who would be mostly immune to such public criticism, if that is indeed the goal.