I personally believe that Golovkin is a 4 round fighter, if Rosado can weather GGG early and put in some body work he might be right.
some people want to think GGG is some kind of inhuman KO machine but when you load up on almost every shot you will get tired. it showed against Ouma.
Rosado might be able to pull it off. Golovkin gets hit with everything and just bulls foward, a boxer should be able to give him problems. GGG has the eraser though so who knows one slip up from Rosado at any point and it's over.