From the article:

“The details of every play (air yards, drops, pressures, etc.) are charted by a team of trained analysts in the ESPN Stats & Information Group. Every play of every game is tracked by at least two different analysts to provide the most accurate representation of how each play occurred.”

These are values that are being determined by unnamed analysts. They are being done I assume by watching film, and then values are created which are not purely objective measures. Additionally, values are not revealed to the public so that they can be determined with any sort of critical review.

Idk what you expect from me dude. Qbr is a better stat the the old quarterback rating, but it’s still just a stat at best, and at worse requires a human element of subjectivity. It also happens some of the people who consulted on the human element are people I don’t like. Please go fellate qbr somewhere else where John Gruden can see and treat you like the genius you think you are