They didn't get their tactics wrong at all, not really any more they could have done. If Millar had got into the break no one would have ridden with him because they know his strengths. If they hadn't chased then they'd have finished even further behind.
I still don't understand why Germany didn't even try. If they weren't interested in getting Greipel to the sprint (or didn't think he could win) then why pick him? Similarly, Australia's tactics were incredibly confusing. Get a man in the break, fair enough. Why on earth Michael Rogers then attacked and wasted all his energy trying to join up with O'Grady I have no idea. Again, in Matt Goss they had a genuine contender for the sprint, so why not give him a chance of contesting it?
If Australia and Germany had ridden with Team GB they would have had a great chance of winning the gold, at the worst they'd have probably been looking at a podium place. As it was, they shot themselves (and GB in the process) in the foot. They were both so concerned with not 'making it easy' for Cavendish that they completely fluffed up any chance of one of their own winning a medal. It was completely brainless, as evidenced by their sudden late panic to try and help Wiggins close the gap when they realised they'd got it completely wrong.