What makes a good startup? Most people say "the idea," "the team," "the technology " and "the market." I think it all may come down to "The Fulcrum" and "The Funnel."
"The Fulcrum" is the core value of your company. Its your unfair advantage. Maybe its insight into a mass of customers, or foresight into the future of your competition, but the fulcrum is the value you create and the value you leverage off of it for others.
"The Funnel" is how you get people to push a lever and realize the company's value. Making the funnel is about building an Experience -- Usability, Findability, Likeability, Ability, Virality, etc -- which leads people to you and ultimately leads people to press the lever which outputs the value.
That is what a startup is about: you may have a great idea and you may have a great team, but if your team doesn't know how the economics of your fulcrum and funnel equate to a rational model to build a large company, you haven't addressed a large enough market problem or solved it in a compelling enough way.