If you can't do the job of your executive chef, put on the whites and get in the kitchen. Don't come out until you can do his job. This means a full understanding of purchasing, food preparation and individual kitchen staff skills. In addition, you should practice working all positions, especially the line. Develop management styles that promote loyalty in your staff to you.
Good chefs have a following of quality kitchen staff.
This staff becomes the production engine that fuels your restaurant's volume. If the staff is more loyal to the chef than to you, you are in big trouble when the chef leaves. Evaluate your menu for balanced kitchen production, make changes that improve quality, flow and staff utilization. Watch kitchen staff very carefully to see that the line layout and staff responsibilities make sense. If your chef is solid, tie his compensation to financial performance.