Rose Wilder Lane

You can't sit on a lead and run a few plays into the line and just kill the clock. You've got to throw the ball over the damn plate and five the other man his chance. That's why baseball is the greatest game of them all.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.