Brad Whittington has an interesting take on how publishers view books. He says that it bothered him that publishers would show enough interest in a book to publish it, but they wouldn’t spend the time and money needed to market it. That is until he realized that publishers offer contracts much like a Wall Street investor purchases stock. The investor wants a diverse portfolio. Most of that portfolio will consist of blue chip stock, the sure thing, but the more risky stock have a greater potential for fast growth, so the investor grabs some of those, just in case one of them really takes off. Publishers will put most of their money in well established authors, but they’ll make a risk investment in some of the unknown authors, just so they have a chance of already having the next bestseller under contract when it takes off. 
I’m sure there are ways in which this analogy breaks down, but I think Brad Whittington’s idea is mostly correct. This model may give us some insight into understanding publishers a little better. And if you are a publisher hoping to succeed in this business, it might give you an idea of how you should structure your talent acquisition. Most of us are not blue chip authors. In part, that means that if we get a contract we aren’t going to get much in the way of marketing help. But it also means that our book may be one of hundreds the publisher is just watching. If it starts to gain momentum, the publisher will likely allocate additional resources to help it along, but if it just sits there the publisher won’t do much with it. I once saw Michael Hyatt refer to Colleen Coble as one of their “important authors.” I suppose that terminology works as well here as any. If you are an important author you get marketing help. If you are an unimportant author you’re going to have to create some momentum on your own before your publisher will take notice.
That’s all well and good, but most authors don’t even have a publishing contract. What should they take from this model? Diversity is the key here. In the stock market, if an investor is already invested in blue chip consumer products, he isn’t going to invest in a more risky consumer product stock. Instead, he might invest in a risky stock in the oil industry or the auto industry. It’s a little more complicated with publishing because each publisher focuses on a particular kind of books, but our best bet as an unknown author is to produce a book that is different from the publisher’s most successful books. It shouldn’t be so different that it wouldn’t fit. For example, if a publisher produces Bible study books, we shouldn’t send them a novel. However, if we were to send them a Bible study book that is different than anything else that is out there, they might take the risk, just to see if there is a market for it. But they aren’t likely to take one that is similar to what they’re already selling.
But this model applies to the important authors as well. Publishers don’t like it when their important authors decide they want to write something that’s a little more risky. If you’re an important author who has been writing suspense and then you turn around and decide you want to try your hand at romance, your publisher isn’t going to be real happy. It’s hard to know how the readers will take it. If it flops, the publisher has not only lost the money they put into the book, they don’t have the income from the sure thing they would’ve been selling if you hadn’t wasted your time in another genre.
Whatever your place in the publishing industry—publisher, important author, unimportant author—this model seems to explain things quite well. So, if you’re trying to figure out why a publisher is treating you the way they are, just think of you book like a stock they might decide to invest in.