Actually, talk to most athletic trainers or physical therapists and they will tell you that ALL pitchers throw with an unnatural motion. That not withstanding, KW is considered the definition of bad mechanics. and Prior was considered as having "perfect mechanics" by most experts, so what does that tell you? It tells me that he was overworked, took some direct trauma to vital areas for pitching, altered his mechanics to compensate, and hasn't been the same since. The direct traumas certainly didn't help, but he would have had issues even if it weren't for the trauma. The more pitches a pitcher throws, the more he gets fatigued. The more fatigued he gets, the more his mechanics begin to degrade. Even if Prior had perfect mechanics when he started the game, throwing 120 pitches was certainly going to give him bad mechanics for that last bunch. Bad mechanics equals a higher chance of injury. Dusty killed Prior.