Football forgives everyone except the cornerback. A guard who gets bull-rushed lines up again the next snap, forgotten by the sideline before he's even back in his stance. A quarterback misses high, and the next snap wipes it clean. A cornerback can play an hour of textbook football, get beat once, and spend the rest of his life explaining that one play to strangers. Marcus Trice, who coaches Houston's cornerbacks, isn't trying to talk his players out of that arithmetic. He's coaching straight into it. "At corner, you may have four or five plays that you really get to impact the game," he…