How to Manage Your Top Performer Who is Also Toxic

By Perminus Wainaina

Today, we are diving into a topic that keeps managers up at night. A situation so delicate, it can feel like being caught between the rock and a hard place.

Let me tell you about a manager named Sarah and her star employee, Alex.

Alex was brilliant. He closed the biggest deals, his clients loved him, and he hit every single target without fail. When Sarah looked at the revenue, Alex’s name was always at the top. Sarah needed Alex.

But Alex was also poison.

He would openly undermine Sarah in team meetings, scoff at company processes, and create an atmosphere of pure tension. He’d hoard critical client information, making his colleagues look incompetent, and once, he intentionally delayed handing over files just to watch a reliable team member scramble. He was sabotaging the business culture, piece by piece, from the inside.

Sarah was trapped. If she fired Alex, she’d lose a massive chunk of revenue and risk her annual targets. If she kept him, her loyal team members, the people who built the company alongside her would quit, defeated by the constant hostility. This is the dilemma: The employee who fuels your growth but is slowly killing your company’s soul.

So, what do we do? We must stop mixing performance with behavior. Your first critical step is to separate them. You are not dealing with a poor performer; you are dealing with a behavioral issue that must be managed through discipline, regardless of his sales numbers.

The strategy is simple, but requires discipline.

1. Formal Documentation: Start logging every single toxic incident. The undermining, the harsh words, the delayed files. Date, time, witnesses. You need solid, evidence.

2. The Direct Conversation: Sit Alex down for a formal meeting. Do not focus on his “bad attitude.” Focus on the business impact of his behavior. Tell him: “Alex, your performance is exceptional, and we value your contribution. However, when you intentionally withhold client data, it creates a workflow failure that costs the company time and trust. This is a clear breach of our company’s collaborative values.”

3. The Zero-Tolerance Line: You are putting him on a Behavioral Improvement Plan. You must communicate that the next single, documented incident of sabotage or hostility will lead to disciplinary action.

Now, the reason Sarah found herself in this trap is because her organization lacked the proper HR structures to handle this situation clearly and confidently from the start.

And that is where we come in.

We don’t just recruit top talent; we help firms put in place the proper HR structures you need to prevent these situations. We design clear disciplinary policies and install performance management systems that make it easy to manage both performance and behavior without compromise.

If your managers are currently struggling with inconsistency, if your policies are vague, or if you feel held hostage by one single employee, you don’t have a people problem, you have a structural problem. Let us help you put the right HR structures in place so your business can thrive on all levels, not just the sales.

Learn more about our HR consultancy services and how we can support your organization.

Perminus Wainaina is a Certified HR Consultant and the C.E.O at Corporate Staffing Services. He helps Directors, executives, and managers solve their people management issues for business success. For more on, visit our HR consultancy services page. For a free consultation meeting on your people management issues, reply to this email.