I disagree, there both quantitive and qualitative KPIs, it clearly sets out the quantitive ones e.g. km ran, number of shots, completed passes, assists etc. As long as the qualities ones are without unconscious bias and by the same team it should be fair?
I am more of a binary advocate. Anything subjective for me brings in an element of error. For the subjective content to be without unconscious bias the same person would have to assess every player in the league. For me it is like reading the form book and then chosing a horse based on it's name.
Download the pdf file, it's a very interesting read.