To tell you the truth, it has always been tough. An author used to be groomed for success. Publishers were willing to see an author through the downs as well as the ups. In today's publishing world, even a multi-published author is judged only by the last book and can find herself unable to sell based on one failure. It is brutal and lots of authors are hurting.
Numbers are the name of the game and everything is on computer.
And the downward spiral begins. I hate questions like this. I am an instinctive writer rather than an analytical one. It is all based on the characters. They control it.