Just being really athletic is not enough for a modern PG. That's to hardest position to make in Basketball right now when it was one of the easiest in 2004 if you had just some NBA qualities. Look at Elie Okobo for example. Look like French Westbrook athletically in Europe. In the NBA, he's doesn't have a place. It's unlikely that he stays in this league after his deal ends.Mader has a nice game, but I don't know if it's going to translate into the NBA. At his size, you need to be about to shoot/score at a high level to crack a rotation, and he hasn't shown that ability, as of yet. Since his game resembles Tony Parker's, it's not really a style of play that's relevant in today's climate either.
I take pick-up games very seriously. I remember players hyping Westbrook as he was dominating pros in UCLA/USC summer pickup games. It's not an end all be all or Michael Beasley would be a superstar but things like that matter. Gilbert touched on this as well about NBA guys and NCAA guys. Giannis to me would have struggled if he signed out of Greece with a team like PITT or Wake because he's a pro player, not a college player.
I do think he's better than a player like Mannion but Mannion's potential as an NBA fit is just much better. We know he can play in an open style game. His athleticism is much better. His passing translates a lot more but he's not polished at all. Ideally, he should have returned to Zona.