This is merely a
guideline, something to help you understand which attributes are important for each player position according to the selected strategy. For example, for GK (goalkeeper), the most important attributes are marked as "A"; so when you are looking to buy or train one, you should focus on these attributes. "B" are less important attributes and "C" are the least important according to the creator of this file.
However, this guideline was created some time ago and based in a different game engine. The game engine has changed in the last couple of seasons so this guideline needs to be revised. It is still useful though if you are new to the GKO world.
Hope this helps.