What the authors of Made to Stick were talking about was using commonly recognized imagery and ideas in the language used to communicate your message. In the book they give the example of Aesop’s fable about The Fox and the Grapes, which is where the term, “sour grapes,” comes from.
The fox story is concrete in that it talks about how the fox couldn’t eat the grapes hanging on the vine above him, just out of his reach. In the fox’s defeat the fox proclaims the grapes were likely sour anyway. The lesson learned was that it’s easy to despise that which we cannot obtain.
My point (really the point of the authors of Made to Stick), is to the extent you’re able try to be concrete in the way you talk about your company’s brand, in the way you display imagery regarding your company’s brand (logo, identity design, etc), in every way you outline the benefits of your products/services, etc.
Give folks clear imagery that is common enough for them to wrap their imagination around. This is extremely important in service companies that don’t necessarily have a tangible product to sell.