It could also be negative thinking. Once you get into this sort of 'rut', you expect to keep doing it, and so you reinforce the behavior in the mind. You need to change that too. A few days off may help as someone already pointed out. If you have someone videotape it (if it is really happening often), you can also pinpoint what the person is doing wrong (if you haven't already tried this). Just need to find a way to stop him from thinking when he knows he has to throw and has the time to start thinking, "I need to make the throw, oh god, just don't let me screw up..I'll be happy if he can get to the ball...I jsut want to get this over with...I don;t want to look like a fool...etc."