The leadership profile for top performing companies may surprise you. Most people think of the headstrong, even pugnacious, personalities that “get things done” as those who will likely lead successful companies. But these qualities do not take companies from good to great.

There are vital qualities to executive leadership, like possessing personal competence, being a good team player, a capable manager, and demonstrating leadership. But the most critical component, and the glue that holds the aforementioned pieces together, is a mix of personal humility and professional will. Together, they comprise what can be called Level 5 Leadership.

Have you ever heard of Darwin Smith? If you’re like most people—even most management gurus—you probably have not. When he became CEO of the paper company Kimberly-Clark in 1971, there were serious doubts about his qualifications. He was shy, awkward, and self-effacing, and preferred the company of plumbers and mechanics to financial wizards at galas and board meetings. He grew up an Indiana farm boy, and eventually earned admission into Harvard Law after working full-time during the day and taking college courses at night.

For the  20 years prior to Smith’s tenure, the company had performed well below the market averages. In the decades that followed Smith’s appointment, however, the company only grew. Within 20 years, company stocks were four times greater than the general market, putting it far ahead of competitors.  

Smith demonstrated a personal humility, but also a tough resolve to see things through. His face-like-flint determination was directed toward the good of the company rather than self-gratification.

One of the most damaging trends in businesses is to bring in celebrity personalities to turn companies around. What you want is someone who looks through a window to recognize how others have contributed to success, and into a mirror when there are mistakes and setbacks. Celebrity executives tend to do the opposite: they put the mirror up when they hear praise, and then look through a window for people to blame when projects implode.

The workhorse does better than the show pony in turning a business from good to great. The track record for celebrity executives with big personalities (and even bigger egos) is actually pretty abysmal. None of this is based on preconceived ideology. It is based on empirical data: all of the good-to-great companies had someone with humility and will during a critical transition process. By contrast, almost all of the good-not-great competitors lacked these qualities in their executives.