It's probably more like these mouthpieces are sending smoke signals to the other camps. If everyone knows what everyone is likely to say in advance, it's easier to not contradict each other.
I saw this reported on ESPN last night. Don't people know how to keep their mouths shut? If he believes this will happen why not remain silent and allow it to happen without putting it out there unless they are trying to influence the testimony by saying they are counting on Pettitte's reputation. Are these guys so starved for media attention that they need to yap all the time about any little thing that comes up?