Every workplace has one. The high performer everyone hesitates to challenge. Their numbers are strong, their output is undeniable, and leadership points to them as proof that the system works. Yet behind the metrics, something feels off. Meetings grow tense when they speak. Collaboration shrinks. Good employees disengage quietly, unsure how to name what’s wrong without sounding “difficult.”
In this edition of Q&A With Jane, we explore one of the most uncomfortable leadership dilemmas organizations face: what happens when excellence in results comes at the cost of team trust. Jane unpacks why tolerating subtly destructive behavior is not a neutral choice, how silence from leadership quietly legitimizes it, and why the long-term damage often shows up only after your best people start leaving.
With clarity and compassion, Jane explains how to separate performance from permission, how to give feedback that addresses behavior without personal attacks, and how to reframe the conversation from interpersonal tension to organizational risk. This piece is not about vilifying strong performers. It is about redefining what performance actually means in modern workplaces, and why results achieved through erosion of morale are never sustainable.
For managers, HR leaders, and employees navigating the quiet cost of “brilliant but difficult” colleagues, this Q&A offers a grounded, practical lens on accountability, culture, and the courage to protect teams before damage becomes irreversible.
A reader writes:
Jane,
I manage a high-performing employee who consistently delivers results. On paper, they are exceptional. Deadlines are met, targets are exceeded, and leadership often points to them as a model employee.
But there’s a problem no dashboard seems to capture. They undermine colleagues in subtle ways, dismiss ideas in meetings, spread quiet negativity, and leave people feeling small without ever crossing a clear HR line. Team morale dips after interactions with them, and I’ve noticed strong employees disengaging or asking to move teams.
When I raise concerns, I’m told, “But they perform.”
How do you handle someone who is excellent at the work but harmful to the people around them?
Thanks.
This is one of the most difficult and common leadership dilemmas. And let’s be honest about the uncomfortable truth first.
A high performer who poisons the team is not a high performer. They are a short-term asset with long-term damage.
The mistake organizations make is treating performance as an individual sport when work is fundamentally relational. Output matters, yes. But how that output is achieved matters just as much. When someone consistently erodes trust, confidence, or psychological safety, the cost simply shows up later, usually as attrition, burnout, or silence.
Here’s how to handle it without turning it into a witch hunt or a popularity contest.
1. Name the behavior, not the personality
Avoid labels like toxic, difficult, or bad attitude. Those shut conversations down and make the employee defensive.
Instead, be specific and observable.
For example:
“In meetings, you often interrupt or dismiss ideas before they’re fully discussed.”
“I’ve received consistent feedback that your tone feels undermining during collaboration.”
High performers are often very good at hiding behind ambiguity. Specific examples remove that shield.
2. Stop rewarding results without context
When leadership says, “But they perform,” what they are really saying is, “We are willing to trade team health for short-term output.”
That trade always comes due.
If bonuses, promotions, or praise only reflect numbers, the message is clear. Behavior is optional as long as results are strong. At that point, the organization is complicit.
Performance conversations must include how work is done, not just what is delivered. If collaboration, respect, and trust are stated values, they must carry real weight in evaluations.
3. Connect behavior to business impact
This is where many managers hesitate, but it is critical.
Frame the issue not as interpersonal drama, but as risk.
Declining morale. Reduced idea sharing. High performers disengaging. Increased turnover.
A quietly poisonous employee rarely explodes. They corrode. And corrosion is expensive.
When leaders understand that this behavior is actively undermining team performance, not just feelings, they listen differently.
4. Give clear feedback with clear expectations
High performers often assume they are untouchable. That assumption grows in silence.
Feedback should be direct, calm, and paired with expectations:
“These behaviors need to change.”
“This is what effective collaboration looks like here.”
“This will be measured alongside your results.”
Importantly, offer support but do not negotiate the standard. Coaching is appropriate. Excuses are not.
5. Watch what happens next
Here’s the uncomfortable part many leaders avoid.
If the behavior does not change after clear feedback and support, you have your answer.
At that point, the issue is no longer about skill or awareness. It’s about choice.
And when an organization continues to protect someone who harms the team because they deliver results, it sends a message to everyone else. Performance excuses behavior. Silence is safer than speaking up. People are replaceable, but numbers are sacred.
That is how cultures quietly break.
Great teams are not built by stars who shine alone. They are built by people who elevate the room, not drain it.
If you allow one person to poison the well because they bring in good numbers, don’t be surprised when the people who could have made the organization truly exceptional choose to leave quietly.
And they will.
Are you facing a tricky workplace dilemma? Write to Jane Harper with your questions on workplace conflict, policy issues, or people management problems. Your situation could be featured (anonymously) in a future column.
Send your queries to: info@thehrdigest.com with the subject line “Ask JANE HARPER.”
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