Effective managers play a vital role in successful teams by creating a positive and productive team environment, assigning tasks, setting clear goals and expectations, and facilitating communication and collaboration among team members. In this paper, we employ a distinctive experimental design to identify the marginal advantage of effective managers, and the specific attributes that yield the greatest benefits to team performance. Despite the increasing importance of teamwork in the modern workplace, there is limited experimental research exploring the added value of managers in raising team productivity.