Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
Recognize that if they failed in that job, it is because of some qualities they have. You will need to understand what those qualities are and make sure they don't apply to any new role. Also, if you learn that they don't have the potential to move up, don't let them occupy the seat of someone who can.
Remember that you're trying to select people with whom you want to share your life. Everyone evolves over time. Because managers develop a better idea of a new hire's strengths and weaknesses and their fit within the culture than what emerges from the interview process, they are well positioned to assess them for another role if the one they were hired for doesn't work out.
Whenever someone fails at a job, it's critical to understand why they failed and why those reasons won't pose the same problems in a new job.