Not the dramatic, headline-grabbing kind. The slow fade. The kind that happens while everyone’s still congratulating themselves on last year’s wins.

A recent piece from McKinsey & Company calls it strategy’s biggest blind spot: the erosion of competitive advantage. And they’re right. Most leadership teams believe they understand their advantage. But belief isn’t measurement. And it definitely isn’t protection.

Here’s the uncomfortable truth: your competitive advantage has a half-life.

You don’t notice it disappearing because it doesn’t vanish overnight. It dulls. It gets copied. It becomes table stakes. What once made you special becomes what customers expect.

And that’s where this connects directly to Seth Godin and his book Purple Cow.

Godin’s argument was simple: in a field of brown cows, a purple cow gets attention. It’s remarkable. People talk about it. They cross the road to see it.

But here’s the part most companies forget: purple fades.

The thing that made you remarkable five years ago is now industry standard. Faster delivery? Everyone has it. Digital experience? Mandatory. Data analytics? Welcome to 2015.

If you’re not careful, your purple cow turns beige.

And the most dangerous moment? When you still think it’s purple.

That’s the blind spot McKinsey is pointing to. Leaders assume their advantage is intact because they’ve built a narrative around it. But advantage isn’t a story you tell internally. It’s a choice customers make externally.

If customers wouldn’t cross the road for you today, you don’t have a purple cow. You have livestock.

So what do you do about it?

First, get brutally specific.

Competitive advantage isn’t a corporate slogan. It’s not “we’re innovative” or “we’re trusted.” It’s market by market, segment by segment. What actually drives preference here? What makes customers choose you over alternatives right now?

Second, measure remarkability — not activity.

Are you investing in things customers would pay more for? Or are you funding internal pet projects that feel strategic but don’t move the needle? There’s a big difference between being busy and being remarkable.

Third, institutionalize reinvention.

Purple cows are not permanent. They’re created. That means you need a system that constantly scans for erosion and asks: what’s becoming normal? What’s getting copied? What are customers starting to expect as a given?

If you’re not answering those questions regularly, the market is answering them for you.

And finally, make erosion visible.

Most companies track revenue, margin, and cost. Few track the durability of their advantage. Where are you losing differentiation? Where are competitors closing the gap? Where are customers becoming indifferent?

Indifference is the early warning signal.

Here’s the call to action:

Stop protecting your old purple cow.

Build the next one before the current one turns brown.

Competitive advantage isn’t a trophy. It’s a moving target. If you want to win tomorrow, you need the discipline to admit when today’s edge is fading — and the courage to reinvent before the market forces you to.

That’s not just strategy.

That’s survival.