This one trait matters to employers more than any other

Likability is only one factor in what makes an employee fit within a team.

Likability at work is overrated.

We've all heard the stories about the boss who does an interview and decides to hire someone because the boss would hang out with that person after work. Strangely, that hiring metric never shows up at the Harvard Business Review.

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What employers and fellow employees really want is something that's also hard to quantify but in my view is even more important.

Likability means someone has a few traits we like--maybe the person's into sports or watches the same television shows we like. Or she has a good personality and some charm. Yet charm and likability fall flat when there is real work to be done.

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What do employers really want? I'll call it "performability." It's a bit difficult to pin down, yet easy to spot in the people around you. I'm defining it this way. Performability is the ability to get the job done no matter what, without causing any stress, confusion, communication problems, or conflict. The person who has it doesn't rock the boat, and works with others in a way that creates a healthy work environment. Performability always trumps likability. It means this is someone who can be trusted, who won't complain, and who knows how to streamline.

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It's important because it's all about the team performing better. It's also something employers can teach and employees can learn. How do I make sure my attitudes, skills, interests, preferences, and personality mesh with the team?

In the end, that's performability.

Let me be clear about this. I'm not talking about productivity. Performability is all about being the person who has fun at work, who fits perfectly onto a team, and who is part of the solution. When you add someone with high performability to a project, things get done. The person the boss hires because of a glowing personality? It's not always someone who fits on a team, despite the importance of that aspect. In fact, the comedian employee who is fun to be around might be a poor communicator or someone who causes conflicts because he or she has so many strong (and possibly funny) opinions. How a person performs on the team is critical, and it requires a variety of skills. Yet the most important skill is making the team better.

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We all know people who don't do that. They gripe and complain, even though they have an MBA. Suddenly, those traits of likability and skill don't matter.

I'll admit that hiring for performability can be difficult, but it's not impossible. For about 10 years, I had to hire people constantly, and I tended to ask a candidate questions that helped me understand whether the person would fit on the team and help everyone succeed. You can't pick one metric for performability. The only way to find out if the person will help rather than hinder is to come up with some scenarios and even a test project to see how that person fits and if she can perform well enough.

Here's a real example. In one of my first jobs at a startup, I ran a graphics design group. It was fairly easy to "test" for certain roles, particularly for photo editing and illustration. I used to have candidates create a simple brochure, but they had access to the team and could send an email or make a phone call. We were a small company, so this wasn't too difficult to arrange. My test was partly to see if candidates produced adequate work, but I knew most of the people we'd even consider had the right skills. Many had a fun personality and were really smart. My main goal was to test performability. Did they send abrupt emails? Did they act proud about their work? Did they cause delays? Could people communicate effectively?

After a test, I'd usually ask the team about the candidate. What they'd say was always revealing. In many cases, they'd say they liked the person, that he or she was fun to be around and knew a lot about Photoshop. Then we'd talk about how that person worked with the team. There were a few times when the candidate was fun and submitted an amazing brochure, but everyone thought the candidate was a pain in terms of communication and conflict avoidance. It's amazing how it could only take one email or one phone call from that candidate to realize there was a low performability. The whole team knew the candidate wouldn't fit.

The idea is not just "works well on a team" but much more important than that. It's a way of analyzing skills, talents, personality, and every other metric and deciding if a person will push projects forward or cause delays. The right candidates fit right in and everything runs smoother; the wrong candidate is like adding glue to the cogs.

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