Wilder has pretty decent stamina if you ask me. He just got hit too many times and it drained him. Wilder has miles better stamina than the likes of Juicy J and Whyte . Juicy J gets panic attacks when the going gets tough and Whyte is pretty much a slob. Id say he is definitely above average in the stamina department. Fury can just plain fight for days. Fury could probably last longer than most when he was 24+ stone.