The very interesting essay by Bly "What the Image Can Do" lists several "powers of poetry" or traits that make poetry work.
1. the image.
2. Frost's "Sentence Sound"
3. psychic weight
5. drumbeat ( or Hall's "goatfoot")
6. the narrative
I am always interested in lists like these as while they seem to capture important elements of poetry writing, they rarely seem complete to me. There are other aspects that seem important that are not on the list. What about the visual / page placement / line breaks /stanza breaks?
Since I spent many years as a musician, I know that the rests are as important as the notes and they need to be heeded for the music to conform to what was composed. I feel that the same goes for poetry. To me the written page works as a score for the aural / oral experience of the poem. What else should be added to the list?
Read some Bly on-line.