Forget all the myths about the book business: the parties, the poring over manuscripts, and passionate arguments. The book business is a distribution business, pure and simple. It's about getting the words and ideas of a writer into the hands of a reader.
In the old days, publishers had to get the books piled in the bookstore so readers would notice them when they came in to buy. They also needed to get them reviewed because that's where book buyers learned about books. Book publishers made nice profits by proving their mastery of everything from getting the cheapest printing and most efficient trucking to having clout with bookstores and reviewers.
Few readers buy books based upon reviews anymore…
What does translate into sales? A direct connection to the reader. That comes from publicity or word of mouth. What publishers pay for when they pursue the high-risk strategy is access to publicity…or their sense that a book will tap into a kind of social currency.