"We all like to believe we are essential to a book's success, but the truth is, we are a marginal factor. The author, and the book, matter most, followed by the media, booksellers and readers. We're facilitators. The most important decisions we make are at the acquisition and positioning stages. That's where sales and marketing experience is most useful and why those executives should be assigned to specific titles at the outset.
"...authors usually write the best promotional copy (they're writers, after all), and they certainly know their readership best. Yet they are underutilized in the publishing process. Empower them. Greg Mortenson and David Oliver Relin's Three Cups of Tea, for example, has been sustained by a dynamic author and a multi-year speaking tour, and the hit Twilight series has greatly benefited from Stephenie Meyer's extensive online promotional efforts. At Hachette, I've had a peripheral view of the Twilight phenomenon. It began with an astute, passionate editor and publisher named Megan Tingley, who read the manuscript on an airplane, and made a pre-emptive three-book deal. The readership built gradually, and with the help of much inventive in-house marketing. But everyone within Hachette points to the author as the driving factor in the books' success."
CHECK OUT Jonathan Karp's excellent piece, 12 Steps to Better Book Publishing, from which this quotation is taken (PW 4-20-09).