The job of a professional baseball umpire requires quick thinking, common sense and confidence. When the ball is in play, the umpire sees the action, assesses the situation and makes the call—all in a matter of seconds. The successful umpire has a thorough knowledge of the rulebook, is even-tempered and is mentally strong enough to handle situations under stressful conditions. A professional umpire is expected to hustle, be alert, be in excellent physical condition and have a neat appearance.