I thought once you have the cap space you can't sign someone else to fill the cap space and then go back over the cap using early bird/Larry Bird exceptions? They assume if you have the cap space to sign the player then you should use it as that nullifies the need for the exceptions in the first place? I could be wrong.
EDIT: I probably explained that poorly, an example would be IF Dwight Howard was a free agent, and signed with the Nets filling the rest of their cap space without Deron Williams signed, they would have surrendered Derons bird rights as you can't sit on his bird exception and go fill that space with Howard to get you to the cap and then sign Deron over the cap?