Good employees are not replaceable. When a company has a truly great employee, that employee carries value that simply cannot be replaced. They carry deep institutional knowledge of the organization. They have extensive product, systems, and process knowledge. They hold client relationships that have been built over many years. They carry tremendous experience on what has worked and what hasn’t worked for the company in the past. And great employees have influence with their coworkers, which when lost, has an impact on the corporate culture.