Over the years, Cuban has hired hundreds of people. So what does he look for in a prospective employee?

"The people that tend to work for me a long time not only are smart, not only are driven, not only are learners," Cuban says.

Granted, that's hardly profound.

Every small business owner--and every boss--wants employees who are extremely intelligent. Who work hard. Who possess a growth mindset, constantly seeking improve their knowledge and skills.

But Cuban also looks for one other quality not every smart, driven, and curious person possesses:

"They understand that the greatest value you can offer a boss is to reduce their stress."

That makes sense at a basic level. As Cuban says,

"Anybody who reduces my stress becomes invaluable to me. I never want to get rid of them. "The people who tend to think that they are invaluable are typically the ones who create the most stress by creating firestorms and creating drama and making things more difficult for me. "If you are stress reducer, you're going to do well. If you're a drama creator, you're not going to do well."

Of course he's right. No matter how talented, people who create drama almost always do more harm than good to an organization--and create more headaches than value for a boss.

They steal ideas. They take credit where credit is not due. They can always find the dark cloud. They invariably find a way to take something personally.

We all know people like that.

But on a deeper level, just being a person who doesn't create drama isn't enough to qualify as a stress reducer. The absence of a negative isn't a true positive; not creating drama is a basic expectation.

Invaluable employees actively help eliminate drama--and with it, a boss's stress.

How?

1. They don't care about (their own) job descriptions.

Stress reducers think on their feet. They adapt quickly to shifting priorities. They do whatever it takes--regardless of role or position--to get things done.

When there's a problem, stress reducers jump in without being asked. Even if--especially if--it's not their job.

2. They tell you what you least want to hear.

The more rungs on the ladder that separate you and an employee, the less likely that employee will be to disagree with you.

For example, your direct reports may sometimes take a different position or even tell you that you're wrong. Their direct reports are much less likely to state a position other than yours. And entry-level employees almost always sing from the company songbook, at least when you're the audience.

Stress reducers know that what you most need to hear is often what you least want to hear.

That your ideas may not work. That your point of view is off. That you made a mistake.

While telling you might increase your stress in the short term, it definitely decreases your stress over the long term.

Because what you care about most is doing what is best for your company and your employees.

3. They sometimes privately disagree...

Debate is healthy. Disagreement is healthy. Weighing the pros and cons of a decision, playing devil's advocate, sharing opinions...every boss wants to hear what his or her team thinks. It's not just enlightening; it's stimulating.

Great employees share their opinions freely. They trust that you want them to--because you and your company benefit from an honest exchange of differing opinions and points of view.

But sometimes those conversations are best held in private.

Stress reducers know not only the right time, but also the right place, to express their opinions.

And once a decision is made...

4. ...But they always publicly support you.

We've all been in a meeting where someone says, "Look, I don't think this is the right thing to do, but I've been told we're going to do it anyway. So let's at least give it our best shot."

After that little speech, does anyone ever give it their best shot?

And we've all seen people hold the meeting after the meeting, where they say all the (negative) things they didn't say during the meeting.

Even when they disagree with a decision, stress reducers don't try to prove you were wrong.

They do everything they can to prove you were right.

And if it turns out you aren't right, that's OK.