Examples of past work. Passion. Can they build things themselves or did they ride the coattails of a large team. Regardless, hold your developers accountable t

Examples of past work. Passion. Can they build things themselves or did they ride the coattails of a large team. Regardless, hold your developers accountable to results. Manage by output not man hours. If within 6 months you don't feel they're a good fit, move on.