One of the most difficult parts of writing a book is making sure that everything is expressed well. There are all sorts of rules – avoid passive verbs, limit the number of adverbs, vary sentence length – but what they all boil down to is “make your writing clear, and help the reader understand what is happening.”
This is particularly difficult when dealing with fight scenes. There are a lot of people who will tell authors that they skip past the fight scenes and just jump to the end to see who survives. For some authors, the takeaway from that is that they can do a crappy job on their fight scenes.