Most of us want accurate information on how we are doing and what we need to do to improve. As managers, how effectively we carry out performance appraisals may have a major impact on how well our unit does and how we are evaluated as managers. Extensive literature has evolved to help us design systems that are designed to result in accurate and helpful appraisals. Yet despite this, comments such as the one above are not unusual. While appraisal is supposed to be objective and accurate, the reality is closer to the manger's comments above.
Many managers deliberately distort and manipulate appraisals for political purposes.
In the real world, managers may have needs other than being completely accurate and rational. Managers giving appraisals have other motives and purposes that may supersede a concern for accuracy. I've used it to get my people better raises in lean years, to kick a guy in the pants, or to pick a person up when down or tell a person he was no longer welcome here. Accurately describing an employee's performance is really not as important as generating ratings that keep things cooking. The mere fact that you have to write out your assessment and create a permanent record will cause people not to be as honest or accurate as they should be.