http://www.thecompletepitcher.com/injury-prevention.html

Poor pitching mechanics also appear to contribute to injury risk.

This includes not only a pitcher's regular mechanics but also mechanical changes that may occur during a game.

Besides a loss in some velocity and usually control, a pitcher will often change his mechanics to compensate for the loss of arm strength or to protect his arm from further pain. 

Look for pitching mechanics changes such as: 

1. The pitcher rushes his motion trying to generate more force with his body and reduce the stress on his arm. It will look like the pitcher is dragging his arm and he’ll have a loss of hand speed because he has disrupted his normal throwing sequence. 
2. The pitcher may shorten his follow through (deceleration of the arm) and not use his normal arm extension upon and after ball release. 
3. The pitcher may not get his hand up into a normal high cocked position. It will appear that he has dropped his elbow during the cocking and acceleration phases. 
4. Between innings, the pitcher may hold or massage his arm displaying pain. With muscle fatigue, a pitcher’s hand often trembles. 
5. Between pitching assignments, the pitcher may be reluctant to throw, or throw properly during dill work, since he is attempting to protect his arm from further stress and pain. 

I suggest that head coaches work closely and communicate with the assistant coaches, trainers, other players, and even a pitcher's parents, when necessary.

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