Roles are held by a person for a selected term (as defined in the domain description). When the term is finished, the role keeper is evaluated based on the role criteria (also defined in the domain description). This can be done either by the role keeper her-/himself, the team or a leader in the organisation. In general, the more data points, the better. And it's never about the person – it's about the role. Sometimes the person is awesome but didn't fill the role well due to the situation, role description or any other reason. Be rational, and compassionate.