The difference between successful business people and those who are not successful is not talent. The difference is that successful people have the guts to move forward, take intelligent risks, and work harder than anyone else.
In all walks of life teams exist to get results. Getting results depends on teams being both productive and positive. Teams can be highly productive running at 100 miles an hour but have low levels of morale.
When you conduct performance reviews, there is no way to guarantee that the discussion will end with both you and the employee in total agreement. This is especially the case if the review involves negative performance.