Understanding staff's psychology could allow you to navigate poor performers in the company. This is because there may a communication problem between an employer and employee.
Understanding staff's psychology can help employees identify their strengths and weaknesses. After identification, you can help them with develop their strengths and delegate their work to other works.
In the end, this would help maximize the amount of contribution and value an employee could provide to the daily business processes, making it both efficient and effective.
Check out this podcast which would discuss more on this.