One thing this article didn't mention: when it came to predictability, NATO aircraft were the polar opposite of Zoltan--they often flew the same routes, at the same times, using the same radio callsigns, day in and day out. This made it very easy for him to predict where an airplane would be. In the case of the F-117, I have heard that the pilot made back-to-back passes over the same target and was shot down on the second pass.
I also heard an apocryphal story about Zoltan: After the war he was "debriefed" (not really an interrogation, since the war was over and he hadn't committed any war crimes, but not exactly a friendly chat, either) in order to learn his tactics. After a while, his interviewers realized that he believed that the NATO forces were so arrogant that they had deliberately tipped their hand to him: he couldn't understand any other plausible reason why they had been so bad at keeping secrets, especially in regards to the movements of their aircraft. When they tried to explain that they had thought they were practicing good security, he refused to believe them and accused them of lying--nobody could be THAT bad at keeping secrets!