Why should small companies be careful about hiring top executives from big companies?

Say you open a small restaurant, slowly earn some money, and want to grow and expand—so you hire a chef from state banquets.
But when they get there, you find out they can’t stir-fry shredded pork with green peppers, and even their tomato scrambled eggs don’t taste good.
You ask what they can do. They say they can cook Buddha Jumps Over the Wall—state-banquet kitchens only do Buddha Jumps Over the Wall—and they still need someone to help as an assistant for the soup.
But your little fly restaurant—who’s going to come to eat Buddha Jumps Over the Wall?