I just watched Ballack's interview about Terry on SSN, and found it very interesting - I'll explain why.
I know a little about body language from my line of work (but I'm by no means an expert).
There are a few things that people can do involuntarily in conversation when they aren't telling the truth which give it away - clear as day. Once you know how to spot it, it becomes very easy to tell when people are being dishonest to you.
Ballack has a very easy nature in front of the camera (probably coz he's a proper arrogant twat), generally holding the interviewer's gaze in a strong, confident manner. However, whenever he stated anything about Terry staying at Chelsea, the conversation they had supposedly had, and Terry's possible motivation for wanting to join City, Ballack closed his eyes quite definitely - not just blinking, but a marked closing of his eyes.
I noticed it first time he mentioned Terry's situation, so I looked for it every time thereafter, and there it was - every time.
That would tell me that he does not have belief in what he's saying - he's avoiding eye contact when he's making a statement that he does not have any conviction about.
This doesn't mean Terry is leaving and Ballack is definitely lying - it just means that he doesn't have a genuine belief in what he was saying to the interviewer.
I think that speaks volumes about the current situation, as Terry has clearly done nothing so far to convince Ballack that he will still be a Chelsae player next season.
Have a look at the interview yourself - I'm sure you'll see what I mean