If you want to build a ship, don’t herd people together to collect wood and don’t assign them tasks and work, but rather teach them to long for the endless immensity of the sea. ~ Antoine de Saint-Exupery
If you want your Team Members to really excel in performance, and blossom professionally (as well as personally), do not simply hand them a role description. No, first and foremost, education him/her on the mission of the organization, the mission of the department, the mission of the squad, the mission of her/him.
To the degree that Team Members see and understand how vitally essential their role is to the success of the mission, they will step forward, with more vision in their eyes, more purpose in their step, and more meaning in their actions.
If Team Members lack vision, and thus demonstrate lackluster daily job performance, it could very well be that you have not fully shared with them just how important they are!