> but is used as another (legalese once you've already given up hope).

because "completely useless or toxic"(from prev comment) is manager's subjective assessment, and company wants to have stronger metric for firing people.

Most of life is subjective. Objectivity is very difficult. You are dealing with people who are mostly wacky. I suppose a weighted decision calculation could be used. How do you measure grumpy gus, chatty cathy, or mean marvin? How do handle the unsober?