Guards with semi-automatic assault rifles pace before the razor wire. Their eyes are trained on the men below: gangbangers, thieves, and murderers who converge on a dusty diamond inside the yard.A man who killed his wife stands on the pitcher’s mound. A jailhouse gladiator squats behind the plate. A dope dealer turned preacherman coaches from the dugout. Behind the backstop, the Aryan Brotherhood, the Nuestra Familia and the Crips and Bloods look on. This is San Quentin baseball.