Espn created QBR… they do own it. it is their personal stat that they concocted… it has a subjective part to it so yes, it is proprietary… their analysts grade QBs on a per play basis. Its not like passer rating where you or I could calculate it based off of stats
The definition of QBR:
“Total quarterback rating is a proprietary statistic created by ESPN in 2011 to measure the performance of quarterbacks in American football.”
“The metric takes into account all of a quarterback's contribution to a game, including passing, rushing, sacks, penalties, touchdowns, and turnovers. Moreover, each play is weighted based on its "difficulty", the context of the game, and the strength of the opposing defense.“