Like i stated DAnny loves Athleticism and defence. Sullinger was just too good to pass up even though he has neither of these qualities.
Joseph is a physical SF that can play tenacious D and loves to jam in thunderous dunks. Can also shoot
Issues with him and reasons why he didn't go higher is that, he has mental lapse here and there. Decision making is not his strongest suit. Maybe in a more structured system like docs, it will be a better fit for him. At worse we get a physical generous sized SF, that can play d and score some in transition