Perhaps I'm misunderstanding the study that was performed, but from the articles it seems that this study has only been going on for 3 years now? In which case, any one sitting at the top of the heap is still pretty likely to have gotten there largely through luck. With a large sample size it's entirely possible for at least a couple of people to 'beat the odds' and get a number of questions correct again and again, without necessarily being any better than those who did poorly.

Even with a fairly significant number of questions being asked and rated, it does not appear to be a long enough study to start suggesting those at the top have better skills as opposed to better luck.