Anything that we dont agree with or does not play into our narrative is pure BS.
QBR accounts for opposing defenses: Quarterbacks who face tougher defenses will have their ratings adjusted upward in proportion to the difficulty of their opposition, and those who face weaker defenses will have their ratings adjusted downward.
By the end of the season, most starting quarterbacks have faced an evenly balanced set of opponents, so their adjusted and unadjusted QBRs will be very close. But there are exceptions, and those are the interesting cases. For example, in 2015, one reason the Panthers were able to finish the regular season 15-1 was that they faced a disproportionate number of weaker defenses. The difference between Cam Newton's unadjusted raw QBR of 70.3 and his adjusted QBR of 65.1 (retroactively calculated) reflects the relative weakness of his opponents.