What's the general consensus on the last question you raised? Would Blizzard be expected to provide that info? What about "hidden" values like your MMR?
I don't know actually. And lawyers I asked give inconsistent answers. I was planning to make one to Blizzard come 25th just to figure out what their process is.
‘personal data’ means any information relating to an identified or identifiable natural person (‘data subject’); an identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person;
The keyword people like to use is "in context", where data is personally-identifiable if it can be used to identify you in a certain context. This... covers almost everything with a unique=TRUE in a database, and any ranking-type systems such as the excellent example of MMR you gave earlier.
