If you have an employee with a persistent performance problem the first question you should ask yourself is, "Is it you or is it me?" Are you as the manager providing enough guidance, direction, support, and coaching? Are you telling this person every step of the way, "Here is what I want you do to and here is how I want you to do it."? Are you meeting with the person often? Are you tracking performance? Are you being honest with the person? If you are doing all of that, and there's still a persistent performance problem, then you can be sure -- It is not me, it's you! And all employee performance problems that are not the fault of the manager fall into one of three categories: Ability, Skill, or Will.
If the problem is ability, here is what that means. It means that the person doesn't have the natural talent to do those tasks. So you have two choices. Choice #1: change the task. Choice #2: change the person.
If the problem is skill, here is what that means. You've got to get that person some training! Or else, get them off the team.
The problem may be will - the will to perform. If you are already meeting with that person every day or every other day, if you are coaching, guiding and directing, and they are still not performing, then that person doesn't have the will to perform in that case. It is either an inside problem or an outside problem. If it is an inside problem, that person just doesn't feel good about him or herself. Then you have to ask yourself, are you a licensed psychological therapist? If you are not, don't pretend to be one at work. Do not try to be your employee's therapist. If you think that person has a problem deep inside, send that person to therapy!
But a lot of times it is an outside problem. Ask -- Is there something I can do for you to motivate you? What could I do to help you succeed? What could I do to motivate you to work smarter, faster, and better? And if that doesn't work, then your only choice is to get that person off the team.