You'd think a 'world champion' with 30+ fights behind him should be able to stop a 12 fight novice who has barely moved beyond domestic opposition. However I don't really think there is that much between them. Joshua has certainly made more progress in his first 12 than Wilder did.
Wilder had to keep his distance vs Stiverne. Current Joshua knocks out any version of Stiverne. I would bet my mortgage on it. Arreola almost finished Stiverne. Joshua would knock-out Stiverne within 6rds. As for Wilder vs Joshua! If people think Wilder has more "skills" than Joshua you're sadly mistaken. Wilder is and always will be the American David Price.
He might at this time KO Joshua, but the fact that you are talking about this fight means that you think Wilder is a very average fighter. AJ is still a nobody on the world scene, he hasn't made any impact on world level and you are talking about this fight? Joshua also has far better skills than Wilder who doesn't have much in terms of skills in my opinion, good jab, great power and not a lot else for me, oh and by the way I really rate both guys.
Joshua stops Stiverne in under 6 rounds. Wilder spent 12 rounds making sure he wouldn't get hit afraid of the canvas he will inevitably meet.