or years, I’ve coached first-line and middle managers navigating issues they couldn’t quite name but could absolutely feel. Everything looks fine on the surface. The team is performing. Work is getting done. You’ve just come in as a new manager or you’ve been settling into your role with confidence…

Yet something feels off.

Suddenly morale dips, communication fractures, collaboration drops, and your boss starts asking why the team seems unsettled.

I’ve seen this pattern too many times. And more often than not, the cause isn’t what managers think.

Most leaders assume toxic culture trickles down from poor senior leadership, political agendas, or resource battles. But in many teams, toxicity begins with something far more subtle, and far more dangerous:

a socially powerful “bad apple” whose influence quietly corrodes the team from within.

And these bad apples are almost always your top performers.

Let me walk you through how to identify them, how I coach leaders to address them, and how to make the tough calls that protect your culture and your credibility.

When the Bad Apple Looks Like the Perfect Employee

Some of the most toxic people I’ve helped managers navigate were the ones leadership praised the most.

They were:

• Hard-working
• Enthusiastic volunteers
• Always looping in the manager
• Socially influential
• Deeply embedded in the team

On paper, they’re stars. Behind the scenes?

They’re stirring chaos:

• Spreading rumors about the manager
• Claiming you’re “micromanaging” or “not listening”
• Playing both sides
• Positioning themselves as the real leader
• Undermining decisions before they’re even rolled out

They thrive on image management. They understand social dynamics. And they make other team members afraid to fall out of their good graces — think of the mean girls dynamic, but in corporate form.

This is the kind of toxicity most managers are oblivious to until it’s too late.

The New Manager’s Sabotage Scenario (I’ve See This Often)

One of the most common cases I coach managers through is this:

You join a new team. First few 1:1s go great. Everyone seems aligned and supportive.

Then, weeks later, things shift. Fast.

In almost every case, the root cause was one of the following:

• Someone who expected your role
• Someone the team assumed would be promoted
• Someone who felt overlooked or “replaced”
• Someone who believes they know the team better than you
• Someone whose identity is wrapped in being the unofficial leader

The sabotage starts subtly:

• “People aren’t sure about the direction…”
• “There’s discomfort in the team…”
• “We used to do things differently…”

Not long after, your team fractures.
And suddenly your boss is asking why morale is deteriorating under your leadership. Why the eNPS score is dropping.

This is when managers come to me wondering:

“Am I being gaslit? Or am I missing something?”

Neither. You’re navigating a covertly toxic influencer, a dynamic far more common than leaders admit.

Values Misalignment Can Also Create Toxicity

Not all toxicity comes from malicious behavior. Sometimes the culture becomes toxic simply because you and the team value different things.

I’ve coached leaders who value: Speed, innovation, bias for action, ownership, results

But their teams value: Consensus, harmony, tradition, extensive testing, avoiding mistakes

Both sets of values are valid. But when they clash without being acknowledged, the team begins interpreting the leader as “disruptive,” “aggressive,” or “risky,” while the leader sees the team as “slow,” “resistant,” or “unambitious.”

This misalignment creates friction that mimics toxicity, and it only gets worse if ignored.

How I Coach Leaders to Identify Their Bad Apple

Over the years, I’ve developed a simple diagnostic framework. These signs almost always reveal an internal saboteur:

1. They manage up exceptionally well.

But peers have a different story.

2. They’re the team’s “informal” spokesperson.

They often speak on behalf of “everyone.”

3. They triangulate.

They bring second-hand concerns but never direct feedback.

4. They’re central to every conflict.

Even when they appear innocent.

5. Performance is high but behavior is questionable.

They deliver, but they destabilize.

6. Team members hesitate to disagree with them.

This is a huge red flag.