When former US Defense Secretary Donald Rumsfeld made his comments about "known knowns and unknown unknowns" in 2002, he was widely ridiculed for producing what seemed like incomprehensible gibberish. Yet since his appearance at a press conference on Iraq and weapons of mass destruction, the phrases he coined that day have demonstrated their usefulness, being employed in an ever greater array of contexts.
Rumsfeld's phrase fits remarkably well with the 2017 MotoGP grid as well. The three categories apply just as well to different groups of riders on the grid. We have the "known knowns" of the Aliens, riders who are guaranteed to win races. We have the "known unknowns", the wildcards such as Cal Crutchlow and Andrea Dovizioso who could easily stage a surprise.
Then you have the "unknown unknowns", a group of riders for whom any result would be imaginable. Given the events of last year, any one of them could end up on the podium, or even winning a race. But they are just as likely to finish outside the points, or anywhere in between. There is no way of knowing on Thursday night where any of these riders might finish on Sunday.