GMAT Essays (AWA)

I have a question and am hoping someone can help. I have a B.A. in English and have been a professional communicator for over 15 years. So, in other words, I have extensive business writing experience. I am trying to wrap my brain around the essays. How do they really score them? I've heard some people say it's by content and structure and others say it's how well you write it.

I know there are many non-native English speaking people who take the GMAT and even with their limited knowledge of the English language, they are able to score between a 5-6. So, I guess I'm asking, should I focus more on the content I put in the essay or how well I write it? What are they really looking for when they score it?

Thanks!