This is in response to the question above posed by 
The first step in dealing with underperformance is to determine the underlying cause of the problem. If this is a new employee you monitor their performance during a probationary period. You use periodic reviews with the employee to ensure that they know your expectations. You have to make sure they have proper training and know how to perform the job. You need to let the employee know if he is not performing up to your expectation and you need to get feedback from them as to what they need to be able to improve.
If this an employee that you have had for awhile, past a probationary period, and they are still underperforming, they have never been able increase in competence and master the job, you will have to consider either assigning them a new position or even letting them go. That is a good reason why you need to have regular evaluations during the probationary period so that you know you have addressed the problem all along and have documentation to support a termination.
If this is an employee who has been with you for some time and has always performed satisfactorily in the past, this will require some investigation as to the nature of the downfall and the underlying cause. For instance, if this employee starts being late to work or missing work, and has never done so in the past, this is a sign of a personal problem. You have to have a job discussion about the behavior and let the employee know what is not acceptable and the consequences that it will have if the behavior continues. This is the time get feedback from the employee and offer whatever assistance is available.
If this is an employee who has been in the past a good employee and is now showing signs of underperforming, again you have to have a job discussion to determine the reason. Perhaps the job has become mundane and not challenging. Of course not all jobs can be made challenging, but this might be a sign that this employee is ready for more responsibility, a promotion, or a more complicated job.
A couple of more reasons that a good employee can become an underperformer:
--A feeling of a lack of appreciation. Employees get told when they do something wrong, they also need to be told when they are doing something right. They also need to feel part of the team and that their contribution is meaningful. Someone with pride in their work and a sense of accomplishment will be a better performer. The solution is to give out appreciation, even a simple thank you showing that you are noticing their contribution.
--Having others in the workplace being an obvious underperformer and nothing is done is about it. When co-workers aren't doing their job and causing others to take up the slack, it causes morale to go down and the good employees lose incentive to work hard. The solution is to deal with the poor performer and hold everyone to the same standards.
The bottom line in dealing with this problem with individual employees is communication, feedback, and followup.
