Power shifts from Ralph to Jack. This is because Ralph fails to address the Beast in us all. He keeps insisting there is no beast. Jack is mistaken in saying they can hunt and kill the Beast, but at least he addresses it. Ralph just expects the boys to do the right thing because it's the right thing. Jack arranges for an outlet for the Beast (hunting), and he addresses the fear by telling the boys he will protect them from the Beast. So, the boys choose to follow him. And once he has them, he will not let them go, for he promises to punish anyone who goes against his will.
What qualities does Jack possess? He is authoritative and sounds as if he knows what he is doing. He is decisive and commanding. The boys respond better to this style than to Ralph's "please do right because it's right" style. In short, Jack succeeds because he offers consequences for noncompliance, while Ralph fails because he offers no consequences.