This is a good question. There are several things the human resource department can do to gain a competitive edge for their companies. Let me list a few of them.
First, if one of the goals is to retain top quality people in a company, then it would be wise to make the structure and culture of the company attractive and comfortable for the employees. The human resource department can do this by knowing what incentives employees want.
Second, the human resource department can also make the company attractive to get people to apply for and consider joining the company. By making the company attractive, it will gain more top quality people.
Finally, all companies have troubles at times. To diffuse the problems will be essential. If the human resource department is organized to help in this area, it will be great making the company attractive as well.