Sports provides visible examples of the futility of accurate performance appraisal. We have athletes who thousands of people devote a huge amount of time to dissecting their strengths and weaknesses and those evaluations are constantly shown to be wrong. Teams are constantly paying free agents tens of millions that completely flop. Others hire someone no-one else wanted for the league minimum and they become a big contributor.
Yes, it isn’t hard to figure out Stephen Curry is a far better basketball player than some bench warmer. But trying to value some non-world-class-superstar is extremely difficult. Yet we have many people that think they can provide a great assessment of exactly what rating their people deserve. If someone is really able to judge people that well they should move into the front office of a sports team because they would pay a huge amount for such talent.
When you understand the challenges with evaluating a complex system it isn’t hard to know that evaluating individuals is not easy. Much of the evidence of individual “performance” is so dependent on impacts within the system that are totally out of even the individual’s influence. Yet it is easy to find numbers within a complex system that can be used to argue for or against an individual’s performance.
The contributions any individual brings to an organization is largely dependent on the system in place (see: 94% Belongs to the System).