Not to be confused with summer scenery at the beach, the "normal curve" is that ubiquitous curve which supposedly can represent the distribution of ability, intelligence, aptitude or other personal attributes of people in society. If you measured a large random sample of people, you'd likely find a normal, or bell-shaped curve with a small number of people at both the high and low ends of the scale, and a large group in the middle. There are many reasons why this distribution happens including: natural individual differences between people, and the "regression effect"-- where over time, extreme measures regress to the average. But unfortunately, the "normal curve" can be used to rationalize management incompetence and inadvertently perpetuate mediocrity.
Business management frequently uses the normal curve to force performance ratings on employees. For example, it's common for middle management to criticize a direct supervisor for rating too many performers at the high end of a performance scale. "There's no way all your workers could be that good! Go back and rate them again." Or the manager insists that employees must be ranked from best to worst -- and then sometimes the instructions are "Fire the worst!"
But think for a while about this practice of forcing a normal curve in management. Does it really make sense? In society at large it may be true that performance takes on a normal curve. But if that is the case, then the performance of a group of employees, without outside influences, can be expected to take a normal curve. But surely the purpose of management practices such as training, supervision and selection, is to intervene in the normal curve phenomenon and get as many employees as possible to perform at the top end of the performance scale. Management's role is to prevent employee performance from taking the shape of a normal curve. Why condone, or worse still, insist on a representation of poor and mediocre performance? It simply doesn't have to be that way. If it is, management is not doing its job.
Isn't school performance similar? If the marks at the end of a university term fit a normal curve, could that mean that the professor was useless as an educator? If the professor had stayed away from the class and left the students to learn using their own innate abilities, perhaps the marks would have been the same! Shouldn't the professor have identified the students who were having trouble learning, and work closer with them to make sure they learned what was required?
If you expect a normal curve of performance, you are more likely to accept such a result as an unfortunate "given". Like a self-fulfilling prophecy, mediocrity will be condoned as natural, and excellence will be rarely expected or recognized.
Don't enforce or condone a normal curve for your employees' performance. Select and develop your employees to do their jobs the way you want them done. There is no need to settle for less. Let your competitors take those who can't measure up.