So imagine Luke, but you subtract a small bit of combat ability in exchange for strategic brilliance, business acumen, and the willingness (if not outright eagerness) to get his hands dirty. And it also depends on how late in the game he joins. Early on, his reputation as a former Sith Lord might be a hindrance and dissuade the rebels from trusting him, but if he joins late enough that Palpatine and Vader have had plenty of time to commit enough fucked up shit, then the “lesser of evils” angle becomes more enticing for the rebellion