That would be more "fair," by which I mean that it would remove the obviously computer-favored dynamic of buzzer reflexes. Of course, it wouldn't make good TV, it wouldn't really be Jeopardy!, and I suspect Watson would lose. Against normal season contestants Watson would probably fair well (in a buzzerless competition), but against human champions Watson wouldn't stand a chance.
There's no way to know what portion of the clues the human contestants knew the correct responses to. I've watched Ken and Brad play extensively though, so I very strongly suspect that they easily knew at least as many as Watson.
I would like some stats about that. As I said, Watson could have correctly answered 84% of the questions, nobody could answer 6% of the questions. That leaves a very thin margin for the humans, if past games are any indication one that is probably not large enough.
