Just like you can’t expect even great products to sell themselves, you can’t rely on your work to speak for itself. Good work usually doesn’t speak for itself- you have to speak for your work. Communicating your ideas in a way that resonates with your audience (which implies you’ve thought about what will resonate with them in the first place) shows them that you understand what they care about. To put it another way, it shows that you “get it.” Managers are more willing to take a chance on someone whom they think “gets it.”