Zhang is 3 years older than Wilder and really not that much better of a boxer. More complete because Wilder is so basic, but Wilder's stand out qualities are greater. Wilder is what he is but the Whyte fight should have proven for good that his performances against Fury do indeed reflect well on him. Zhang had a Pac vs JMM 1 type performance except instead of being against on of the best mexican fighters of all time it was Jerry Forrest.
A 280lb big man isn't gonna be stopped by a little basketball player. Eric Molina was defeating the hydraulic can crusher, no way a silver medalist is losing on points vs Wilder.
Both Cammarelle and AJ have hurt him in their amateur fights, a puncher with speed + enough height and reach is a bad match-up for him.