Rumble and Francis? are you out of your mind? They're some of the hardest hitters the sport has ever seen. Maybe it's because some guys simply have good chins and it's damn near impossible to KO everybody you fight, especially when you're against the best the world has to offer. There's a couple factors to take into consideration when it comes to how a strike lands, too. If I remember correctly, Cormier was moving away from AJ when he got dropped. If he was just a little bit closer, he probably would've been put away.
Francis barely landed anything good on Stipe also, but if he did, guaranteed Stipe would've been hurt. There was actually a point where Francis landed a shot that truly didn't have that much on it overall and Stipe wobbled. Oh and I picked Stipe to win, he's one of my favourite HW's and has been for years unlike all these other n00b fans that only jumped on recently after doubting him for a long time since he lost to Struve.
Cliffs:
Rumble and Ngannou hit hard as fuck and you're crazy for thinking their power is overrated.