There's a lot to unpack in this article, but one thing caught my eye. In the "The Ultimate Question 2.0" book the author claims that NPS needs to be considered

There's a lot to unpack in this article, but one thing caught my eye. In the "The Ultimate Question 2.0" book the author claims that NPS needs to be considered as a relative measure to competitors. So if we follow this advise, United needs to aim to have the highest score accross all airlines. To give an example, an NPS of -20 is decent if competitors have below -30.