One possibility would be analysis: who is talking to whom and in what sequences are these conversations happening? Are there White House supporters talking to congress? Who is leaning on whom? Does the White House or their party need to focus efforts to chastise or woo any of their own? Who is the weak link in the opposition? Who are the sources propagating the calls in the opposition? Etc...
So, I speculate this could help the unscrupulous even without hearing the actual conversations...maybe use some imagination based on this:http://www.freerepublic.com/focus/f-news/3019994/posts
There is no way one could find out who is leaking by using phone logs only.
Without phone conversations one does not know what the participants are
talking about. Period. Without a confession, a wire or a recorded conversation, there is no proof of a leak. It is true you might get patterns.
But patterns of what? How would you know the difference between a legitimate
News interview from a leak? You can’t.