What to do when your top performer is toxic
One of the fastest ways to lose your best people? Keep a high-performing jerk on your team.
When dealing with a toxic employee, the idiom, “one bad apple spoils the bunch” has never been more apt. One study showed that toxic culture was the single biggest predictor of employee turnover, 10 times more impactful than compensation.
While occasional conflict or frustration is normal, toxic behavior is persistent, disruptive, and often contagious. Left unchecked, it can erode trust, drive out talent, and put your long-term success at risk.
The Cost of Keeping a Toxic Star
I recently worked with a senior leader—let’s call him Jonathan—who was grappling with this familiar dilemma:
What do you do when your top performer is also your most toxic employee?
One of Jonathan’s managers, Edward, was delivering great results. But Edward’s emotional volatility, combative tone and public put-downs had created a walking-on-eggshells environment on. His team was unraveling.
The impact was clear. In just one year, three people have come and gone through the same role — and the last person only lasted 30 days!
Jonathan knew that if he didn’t act, Edward wouldn’t just damage the team - he could become a legal liability.
If you’ve ever been in this situation, you know how difficult it can be to navigate. Here’s how to identify toxicity on your team—and what to do about it.
How to Know When It’s Toxic
Toxicity isn’t just about conflict or frustration. It’s persistent, disruptive, and contagious. And it often gets normalized—until it’s too late.
MIT researchers identified “The Toxic Five,” based on 1M+ Glassdoor reviews:
Disrespectful: A lack of consideration or courtesy for others.
Unethical: Dishonest behavior, or a lack of consequences.
Cutthroat: Backstabbing or ruthless competition.
Abusive: Bullying, harassment, and hostility.
Non-inclusive: Inequity, favoritism, or exclusion across gender, race, age, disability, etc.
Take this client story as an example: A coaching client's former boss—let's call her Jan—was the longtime CTO who helped lead the company to its IPO. When a new CTO was brought in to take the company forward as a public entity, Jan was demoted and took it poorly.
She openly undermined the new leader, skipped a team offsite, and made her discontent clear. The tension deeply affected the team, especially my client, a VP caught in the middle.
Eventually, the CTO offered Jan a generous exit package that honored her past contributions. The result? The team dynamic shifted dramatically—so much so that people referred to meetings as “Before Jan” and “After Jan.”
Taken together, behaviors like these don’t just create a difficult work environment, they signal a deeper cultural rot.
Ask yourself: Have any of these behaviors become “just how things are” on your team?
What to do when a high performer turns toxic
If a team member is both toxic and underperforming, the decision is simple.
But a top employee?
That’s when things get complicated. You don’t want to lose results—but you also can’t afford the cost of dysfunction.
If, like Jonathan, you’re open to giving this person a chance to change, you’ll need a clear plan.
1. Diagnose the systemic impact
Toxicity isn’t just about one person being “difficult.” It’s about how their behavior ripples across the team.
Zoom out:
Has morale dropped?
Are people walking on eggshells?
Have strong contributors become disengaged—or worse, left entirely?
These are the real costs. And they’re often invisible… until it’s too late.
2. Separate results from behavior
High performance doesn’t excuse harmful conduct.
Leadership, collaboration, and respect are part of the job.
You might say:
“Your results are strong, but the way you’re achieving them is hurting the team and limiting your long-term potential.”
3. Be clear and direct with feedback
Toxic employees rarely see themselves as toxic. That’s why vague feedback doesn’t work.
Name the specific behaviors, not the personality.
Instead of:
“You’re intimidating.”
Say:
“You often interrupt others during meetings, which shuts down participation.”
Set a short timeline for visible change (30-60 days), and document the plan.
4. Offer support - with boundaries:
If they’re open to change, give them support—but with structure and accountability.
For Edward, I recommended a six-month coaching plan that included:
A 360 feedback assessment to surface perception gaps
Clear behavior-based goals with milestones
Confidential 1:1 coaching sessions
Three alignment meetings to check in on progress with me, Edward, and Jonathan.
It gave Edward a path forward—and Jonathan a way to lead with both empathy and clarity.
5. Know when it’s time to let go
If there’s no behavior change, don’t wait.
Keeping someone because they deliver results isn’t leadership, it’s fear in disguise.
High performance that undermines culture is a short-term win and a long-term loss.
And no one—no matter how much revenue they drive or how many deadlines they smash, or how “innovative” they appear—is worth that cost.
6. Rebuild safety and reestablish agreements
Whether the person improves or exits, your job isn’t done. You’ll need to address the elephant in the room so your team feels secure.
You need to:
Address the situation directly (not just let it “blow over”)
Re-anchor to your values
Explain the “why” behind your decision
Because people notice. And they remember.
Ask yourself: If someone asked my team what this culture stands for—what would they say?
Final thought: protecting your culture is leadership
To quote Simon Sinek, “Leadership is not about being in charge. It's about taking care of those in your charge."
Toxicity is never just an individual issue, it’s a systemic risk. And tolerating it is a leadership decision.
So choose to protect your people. They will thank you with their trust, loyalty, and best work.