Source: PWInsider Elite
It’s said that a big part of why Dolph Ziggler isn’t getting pushed is one of the same reasons that Christian isn’t being used – his history of injuries and concussions.
It was said that WWE can’t push Ziggler and trust him a top guy because he’s injury prone and had a history of taking time off. This applies to a few other talents as well. There’s a feeling that some talents are just “snakebit” in that regard.