This grading chart is just a guide. Dog Food Analysis
Dog Food Analysis - Reviews of kibble explains the process you mentioned a little further, here's an example of Acana Grasslands: The first ingredient in this food is a named meat product, in meal form. There is a second meat ingredient third on the ingredient list, and fresh fish products further down the ingredient list. These are, however, inclusive of water content. Once this is removed, as it must be to create a dry food product, the ingredients will weigh around 20% of their wet weight, and may be more accurately placed further down the ingredient list than indicated.