A while ago we wrote a Medium post summarizing our CSCW'2018 paper on quantification in League of Legends. It's here. In the paper and the blog post, we discussed the complicated relationship players develop with their numbers, individually and collectively, positively and negatively.
In the paper, we only wrote briefly about how interpretation of numbers is a situated practice that draws heavily from players' own knowledge and context. There is so much more to say about the various factors one player could use to analyze a number, and each play might develop his or her own theory on how to do interpretation.
Right now most of the tools that I know of use their own formulas to calculate a score, such as op.gg's OP Score and estimate MMR. The scores do not necessarily match players' perceptions and experiences. It would be much more fun if they allow players to customize formulas aligning with their own theories.