'Street was hired by Blizzard Entertainment in February 2008, and was the lead systems designer on the MMORPG World of Warcraft until November 2013.
He described his role at Blizzard as, “Systems design specifically is everything that is not level, story, quest, PvP or encounter design. My team handles everything from mechanics to items to trade skills to achievements to UI design.”’
What changes happened to WoW, with regards to Systems Design, such as Heirlooms, LFD/LFR, Tokens, etc. during this time. Think this through, and look at the history of the changes."
Ref: https://en.wikipedia.org/wiki/Greg_Street#cite_note-linkedin-9