Actually Rusev isn't injured. He was going to come back and challenge Orton at MITB but they went with Mahal instead, leaving the crack creative staff to come up with a new return story. Orton could have kept it a bit longer and things would have been fine. I don't have an issue with Mahal becoming champion but you have to win SOMETHING before you're just thrown into the World Title. It can work very rarely if someone has a special quality but that's not the case here.