Traditional publishers' decisions about which manuscripts to accept and which ones to pass on can be mystifying to writers.

Sure, there are a few things that seem to tip the balance in favor of "yes," like loud events, likeable characters and a plot that pulls readers constantly forward, making those pages turn.

Yet vast numbers of well-written books with all those qualities wind up in the "pass" pile every day, leaving authors to second guess themselves and to feel confused, dejected and...