The task of management and executives is not to increase their expertise, but to lead people to raise them. It is similar to the relationship between a teacher and a pupil. The teacher does not have to know everything, but he has to be able to lead his pupils to higher performances and he must understand where the pupils will find detailed information on the topic. Then they evaluate their work and performance. And that's from all sorts of perspectives. Likewise, this should also take place at the level of labor relations and performances. This will help you with feedback that can assess your subordinates effectively and in a high quality.
The methods of execution are different
We can use the relationship of teacher and pupil again. The evaluation factor is definitely a sign, but it is not the only means to evaluate. An appraisal interview with active participation of both parties is far more effective. You get a lot of information about which you didn't even have any idea. This will give you a different view of the person you know only from the machine and under the numbers of its performance. You will find its life attitudes, its behavioral patterns that are raised to be just ignorance. Think about the system of communication in your company, the needs and desires of your subordinates, be interested in your subordinates and from a different perspective than just the work. You'll be surprised.