When an athlete or team is threatened with consequences should they not perform well, they will consistently fall apart when the game is on the line. Threats only serve to distract the athlete from the task at hand and get them to worry about the consequences for failure. Instead, challenge them. Give them the message, which is implicit in any challenge that you think that they can do it, that you believe in them. Athletes will most frequently rise to your challenges and respond poorly or inconsistently to your threats.
Most stress related performance problems are a direct result of faulty concentration.
Help your athletes concentrate on specifically what they have to do to play well.