Ngannou just inexperienced and makes bet on his strike power and his punchs in MMA probably the most dangerous. He "gently" touched Stipe and it was enough for Stipe to feel it. If he starts to work on his stamina and improve his TDD, he will likely win the belt. Even if he does not change anything in his training, he will still be dangerous for all fighters in HW, especially for the strikers. And also Nganon has an iron chin