Give them credit and enough room to get on and perform. If anyone really does not comprehend the performance standards of their job - then a more detailed, MbO type approach is a very useful means of defining expectations and targeting. Key standards need planned maintenance work doing on them. Maintenance review can be very creative. There is potential for continuous quality improvement.
New projects are likely to be bigger programmes.
The whole role may change as the individual is perhaps relieved of some routine tasks to concentrate on a larger project. Remember an individual can only handle so many new projects at any one time. Too many and the projects will conflict. If people understand the standards or targets they are being asked to attain then they will be more focused and understand the efforts that are needed. Provided these have been discussed, are realistic and attainable within the scope of what be done and the person wants to do them, then they are more likely to engage the person's motivation.