To understand what a publisher seeks in an author, you first must understand the traditional publishing deal. At a basic level, it’s a business deal. You might even call it a financial deal.
Look at it this way: You have a product you want to bring to market—a book. You want someone to finance the creation and production of that product. So, you go looking for an appropriate venture capital partner—a publisher.
The publisher, on the other hand, seeks someone with a viable, meaning marketable, product who will be a good business partner. A good business partner, in this case, is someone who can complete the creative end of the production process—write the book—but who can also help the product succeed—sell the book.
To land the deal, you give the potential venture capital partner a business plan, in this case a book proposal, for your product. He evaluates it. If he finds it to be a sound investment, he offers you a contract. If you like the terms of the contract, you sign it, and the two of you go into business together.