A project manager requires many skills in order to succeed. There is no one sole skill that will allow the project manager to be successful. As emphasized in the PMBOK, effective project managers require a balance of technical, interpersonal, and conceptual skills that help them analyze situations and interact appropriately. In addition the project manager requires a balance of interpersonal skills (e.g. leadership, team building, communication, motivation, decision making, etc.) in order to do their job successfully. The project manager can be a great communicator, but if he/she lacks other interpersonal skills such as decision making, leadership, etc., it will be hard to succeed. For this reason I think becoming a project manager is tough, it takes time and experience to master all skills.