Everybody gets concussions b, even AJ Lee had multiple concussions there.
Cena has had multiple injuries, Orton's fragile ass has gotten injured by slamming his arm on the mat, riding a motorcycle, and taking out the trash, Undertaker has a glass hip, Edge had a bad neck, Christian had concussion issues, shyt Batista got injured right as he was going to join Evolution, that didn't stop Evolution from happening.
Point is, every wrestler has nagging injuries, every wrestler can get injured, some we don't even know about so no need to single Balor out because he recently got Worldstar Elbow to the side of his face.