Let the design team be the design experts. Your job is to be the business expert. Ask them how their design solutions meet your business goals. If you trust your design team, and they can explain how their recommendations map to those goals, you’re fine.
I have always maintained that Design and Marketing go hand in hand. Any designer looking to become more business savvy can get quite far if he or she starts with some marketing knowledge. Mike Funk writes:
Marketing is a framework for the organized delivery