Best Buy, the once mighty retailing giant, is suffering.

From a market valuation perspective, it’s shrinking before our eyes.

The company is in turmoil for a lot of reasons, but I can boil them all down to a single major reason which is, simply, the great strategy and marketing lesson to take away from this story:

Best Buy has not leveraged its one great strength in the world.

In fact, Best Buy has actively, aggressively, worked against its great strength.

Its biggest strength, of course, is its retail stores.The brick-and-mortar environments where consumers can walk in to and experience a wide range of products from countless manufacturers. Test, touch, feel, ask questions, get help. That’s what people would come to Best Buy to do.

Thing is, Best Buy hasn’t set up the stores that way. It’s mostly just product boxes (which the Blue Shirts read with you). There’s nothing approaching the product interaction and employee training on display at Apple Stores.

And so, while Best Buy worked on its e-commerce business, investing many millions to build infrastructure and marketing to compete with Amazon (an impossible proposition), its retail stores languished.

Best Buy stores today look very much how they looked 10 years ago.

The customer service clerks are just as unfriendly.

It’s just as hard to return something (when one can go to Costco and return something nine months later; or on Amazon, within 30 days, no questions asked).

Best Buy neglected its one great strength.

So here’s the lesson for us: identify your great strength. What is it? Writing? Speaking? Delivering? Dancing? Making people happy? Once you know it, there’s only one thing to do: exploit it like crazy. Focus on it. Develop it. Leverage it. Put it front-and-center.

Because if you don’t, your greatest strength can become a weakness in no time.

Just like it has for Best Buy.