The holy grail for leadership is to develop a team of self-motivated, highly accountable top performers. But if you ask any manager if they’ve ever had to deal with an underperfrormer, they’ll tell you, “Of course I have.”

In 1985, I owned another company before starting my coaching firm. I was responsible for a team of sales managers, along with about 50 salespeople. Like a consummate sales leader, I was always recruiting.

Since I was always in interview mode—which allowed me to hire based on choice rather than need—I eventually found someone I perceived was a great candidate. “Peter” soon rose up the ranks and became our top salesperson.

Over time, the two of us became good friends. We grabbed meals together, went out socially and I even went to his wedding. I was there when his first child was born.

He was so good at his job that, when he approached me and asked for a new company car because of all the driving he did as an outside salesperson, we bought him a Lexus. We promoted him to team leader, someone who was responsible for the training and development of new salespeople.

After about two years of what I considered to be a great working relationship, something shifted. I noticed a change in Peter’s attitude. It began to affect the morale and performance of the rest of my team. His positive, generous and supportive disposition disappeared practically overnight. He became arrogant, selfish and self-centered. Still, he continued to outperform every salesperson on the team.

My partners and I justified his behavior by viewing it as a phase—something that happens when a salesperson gets a taste of success. He was at the top of his game, and he was making us a substantial amount of money. We were seduced by his productivity and success, and failed to recognize the collateral damage he was leaving in his wake.

Instead of investing my time supporting and praising Peter for his contributions to our sales goals and the team, I found myself dealing with the negative impact he was causing amongst his peers and even with customers. I couldn’t avoid the ongoing barrage of disconcerting comments, phone calls and attrition of good people. I started hearing comments circulating throughout the office, such as:

• “Peter gets preferential treatment.”
• “Peter’s ego is so big, it’s amazing his head fits through the door.”
• “Peter makes fun of the other salespeople who are not doing as well as he is. He thinks it’s funny, but his comments are really demoralizing and, quite frankly, hurtful.”
• “Peter can basically do anything he wants. I can’t remember the last time he attended a sales meeting.”
• “Why does Peter get to take time off to play golf, while the rest of us are working?”
• “You guys bought him a brand-new Lexus. Do you know he’s using the car for his personal use as well?”
• “It’s not fair that Peter keeps getting all the good leads.”
• “I know for a fact he’s not turning in and filling out the contracts and paperwork according to protocol, and that you guys are doing it for him.”

I asked Peter multiple times what it would take for him to get back to where he was. The Peter who cared about the rest of his team. The Peter who was more positive, humble and authentic, even in the face of success. I sensed he really didn’t care.

“What do we do?” I asked my partners. The problem was getting worse, and still we continued to tolerate his behavior. Even when Peter decided to use my office to make sales calls without my permission, and then yelled at me in front of the team for interrupting him while he was on a call, we still didn’t terminate him.

Soon after this incident, Peter’s performance started to slip. He wasn’t showing up for work every day. We kept hearing excuses. “My wife works and I have to take care of the baby.” “I’m too sick to come into work today.” “I’m still running appointments but I don’t need to come into the office to do that.”

It wasn’t until I went out on an appointment with Peter that I experienced a defining and unforeseen moment. We still had a relationship, even though I knew it was deteriorating. He drove the Lexus to the appointment. While sitting in the passenger seat, I teased him about the way he was taking care of his car. It was an absolute mess. I opened the glove compartment only to find more disarray.

Then, I opened up the armrest between us. I saw some business cards, assuming they were the ones we gave him. Imagine the shock I felt when the business card listed his title as “Owner/CEO” of a different company.

It didn’t take a detective to figure out what was happening. Peter was taking the leads we gave him, using the car that we bought for him to go on these appointments he scheduled, then closing new business using contracts that were written up and signed by the customer under his new company name.

I coach people not to take things too personally at work. When they start defining themselves by their career, I coach them that their career is not their life or identity—it’s just what they do. But that’s today, not 30 years ago.

The truth is, I was devastated. I was hurt. I was shocked. I felt like an idiot. I felt violated. Here I was thinking Peter was a friend, someone I trusted, someone we took such good care of, someone I supported unconditionally because of our relationship and his stellar performance. In an instant, all that disappeared. He destroyed our relationship and became my adversary, instead of the ally I thought he was.

There was no more justification, no more forgiveness and no more chances. We took immediate action and terminated him on the spot. We tried to unravel the damage he caused. We called all the customers he had contacted in an attempt to recapture the business he stole from us. The sales team wasn’t shocked when Peter was terminated—they practically celebrated. “It’s about time!” was the resounding theme.

Sometimes, we don’t want to see the truth. We don’t want to notice the proverbial writing on the wall. We wind up justifying and tolerating people’s toxic behavior until it reaches a destructive breaking point. Even though Peter continued to sell like a champion, he was truly an underperformer.

What defines an underperformer? It goes beyond hitting or exceeding sales goals and business objectives. As a manager who is responsible for the success, culture and performance of your sales team, you have to consider not only how the person is performing on paper, but also who they are—and how their behavior impacts the people around them. Carefully consider the negativity they’re spreading, the turnover they’re causing and the fires you continually have to extinguish that cost hours of your time.

Then, think about how tolerating bad behavior impacts the rest of your team, their performance and you. Inadvertently, you’re sending the message that this unacceptable behavior is acceptable—that you’ll allow it, without consequence. You’ve lowered your standards and expectations, and you’ve granted permission for others to act the same way.

You’ve now incurred a deeper cost. You’ve compromised your integrity and the standards you try to uphold and model for the rest of your team. You’ve lost the trust and respect of the people you manage.

No one likes to lose a top performer, let alone fire them. But we can’t let them hold us hostage, either. At some point, you need to ask the question that will help you make this difficult decision. Rather than ask what’s best for you or for a person like Peter, ask yourself, “What’s best for my team and for my business?” The answer should be glaringly obvious.

Keith Rosen, CEO of Coachquest, has written several best-sellers, including, “Own Your Day” and “Coaching Salespeople into Sales Champions,” winner of five International Best Book awards and the No. 1 best-selling sales management coaching book on Amazon.