One thing in particular resonates with me now, because two of my clients received rejections from agents today.
Burroway discusses the difficulties of getting published in recent years, and has this to say:
"The agent is now less an advocate than a buffer between the publisher and the writer's unrealistic expectations... Mergers, takeovers, and the disappearance of companies have become commonplace."
So publishers squeeze editors, who squeeze agents, and sadly they put the squeeze on the writers. High hopes are dashed, because only those with a book that will be the road to success for the agent, editor and publisher will see the light.
That's bad news but points again and again to the need for platform-building and doing good agent research.