\u201cThe graveyards,\u201d General De Gaulle once ironically observed, \u201care full of indispensable men.\u201d Maybe so, but the same may not be so easily said about organizations whose success did depend on irreplaceable managers and staff.\n\nTake, for example, Apple. Under Steve Jobs it created the iPod, iPhone, App Store, and iPad \u2014 products and services that ranged from radical departures to entirely new concepts.\n\nUnder Tim Cook? What his Apple has introduced to the marketplace are copycat items: A streaming service, new smartphone models, hybrid tablet\/laptop \u2014 fine products, I\u2019m sure, but not particularly innovative.\n\nAnd so far as its financial performance is concerned, Apple\u2019s Return on Invested Capital has diminished dramatically under Cook, from an astronomical 443% under Steve Jobs to a \u201cmere\u201d \u2014 which is to say superior \u2014 183%.\n\nSo, from the perspective of Apple\u2019s board of directors, Jobs was irreplaceable. From the perspective of the digital marketplace, on the other hand, he was, well, irreplaceable.\n\nThe great and the irreplaceable\n\nOf course, as most Jobs-related anecdotes go, this is statistics with a sample size of one. Instead, let\u2019s look at the organization you lead. Depending on the business expert I\u2019m listening to and the day of the week, I\u2019m told three truths:\n\nMy own firsthand experience is quite different. It tells me that:\n\nBut isn\u2019t there a difference between great employees and irreplaceable ones?\n\nThe algebra of irreplaceability\n\nBrooks explained the math: The number of personal relationships in a team of size n is n(n-1)\/2, so a team with 10 members contains 45 personal relationships between pairs of employees. Or, each team member has a relationship with every member (n) excluding themselves (-1).\n\nSo, doing a bit of algebra, when you replace one employee in a 10-member team with someone new, you\u2019ve replaced not 10%, but 20% of the team when you measure team size as the number of relationships in it.\n\nEspecially if the employee you\u2019ve lost is a great employee, you\u2019re looking at, not a changed team, but an entirely different one. If their replacement is only average, the new team is still far less effective.\n\nThe conclusion is as obvious as it is rarely practiced: Treat your best employees as if you\u2019re trying to recruit them, every day of every week.\n\nTreat them that way because if they\u2019re that good, other employers are trying to find and recruit them, every day of every week, too.\n\nWhat makes a great employee\n\n\u201cGreat employee\u201d is easy to type. It\u2019s less easy to define. Here\u2019s a short list to get you started. Scrub it by discussing the question with your leadership team.\n\nThe habit of success: Some employees seemingly don\u2019t know how to fail. Give them an assignment and they\u2019ll figure out a way to get it done.\n\nCompetence: As a general rule, it\u2019s better to apologize for an employee\u2019s bad manners than for their inability to do the work. Without competence, employees with a strong success habit can do a lot of damage by, for example, creating kludges instead of sustainable solutions.\n\nFollowership: Leadership is a prized attribute for employees to have. Prized, that is, if they\u2019re leading in their leader\u2019s direction. Otherwise, if you and they are leading in different directions, all your prized leaders will do is generate conflict and confusion. Followership is what happens when they embrace the direction you\u2019re setting and make it their own.\n\nIntellectual honesty: Some employees can be persuaded with evidence and logic. Others trust their guts instead. That\u2019s a physiological error. You want people who digest with their intestines but think with their brains.\n\nTeam orientation: You want employees who support their team, not those who compete with it.\n\nNot that kind of irreplaceable: Great employees are and should be irreplaceable, or nearly so. But there\u2019s another kind of irreplaceable employee \u2014 those who hoard information and techniques so that getting rid of them is impractical. Take all steps necessary to make these irreplaceable employees replaceable. Then, as soon as you can, replace them with the desirable sort of irreplaceable employee.\n\nThe \u2018Golden Rule of Recruiting\u2019: Don\u2019t settle\n\nFail to fill an open position and everyone will have to pick up the workload. So it\u2019s tempting to sigh, shrug, and hire someone who seems adequate.\n\nBefore you go through with it, ask yourself: Is adequate going to be good enough over the long haul? Or are you better off waiting for an applicant who will, like the employees you already have, be irreplaceable?