I'm not sure I understand the question so I'll break down the quote from the article: > It’s figuring out what it sees and dismisses that might still be useful

I'm not sure I understand the question so I'll break down the quote from the article: > It’s figuring out what it sees and dismisses that might still be useful. The dream of any computer-savvy chess player is to discover a string of moves that an engine doesn’t necessarily favor, yet taps into a line that their opponent hasn’t prepared. The first part ("discover a string of moves that an engine doesn’t necessarily favor") is algorithmically trivial of course. Just print out all the lines the algorithm discarded. At this point I think you can even narrow your options based on a heuristic like, as you suggest, diversity of variations. But here comes the difficult question: which of the remaining lines is "still useful"? That alone requires massive insight. But of course, tournaments at the GM Level require hyper-specialized preparation; at WCC, each of the two contestants has the luxury to obsess over the other's style. At that point in their analysis, not only are they trying to evaluate what line is still useful but, even further, what line is their opponent likely to take. This gamesmanship is sort of like boxers studying each other, figuring out their opponent's chin is open after a jab and drilling the hell out to exploit that fact. (Note: I'm not a ranked player, just an enthusiast. I've dabbled a bit with Chess engines during the WCC 2014 and a bit more beyond but my knowledge is in no way state-of-the-art.)