#4 He can't connect linguistically
Vince even said it himself in that infamous podcast with Stone Cold. Cesaro isn't over and can't get over because of his lack of linguistic skills. Of course, that's not to say that anyone who can't speak English can't be a star.
Look at Andre the Giant, he barely muttered a word and he's arguably one of the most famous names in wrestling history. But he had the physique to create an aura about him, Cesaro has nothing.
Besides the physique aspect, to not connect to the fans with words he must at least have a certain type of aura & charisma about him, he doesn't. There's no aspect of him that makes people travel the world to come and watch him.
Wrestlers with half his ability have had triple the charisma he has. Take for example, Hulk Hogan, he could barely use two moves in the ring but his aura encapsulated billions worldwide.
What makes Sting special? His first AEW opponent opens up RIGHT HERE.
