If fieldpoint impact = broadhead impact points, does that = perfect tune??????
Not perfect, but close. Assuming that the arrow is spined correctly, that the arrow is true, and that your form is relatively consistent, bad broadhead flight is often a symptom of a poorly tuned bow.
I think it was Barry Wensel who suggested that you should take the largest, widest, and most likely to plane broadhead and use it to broadhead tune. Once that head is tuned in, an archer can be fairly confident that all other heads will follow.