Should a pitching coach fix what isn't broken? In other words, if a pitcher is performing well in spite of a mechanical flaw, should a coach intervene by making a correction? Baseball pitching motion troubleshooter Angel Borrelli responds to that "rule" with a new one: "when it breaks, let's fix it!" In the fourth episode of The Fix: Season 3, Angel defines platelet-rich-plasma injections, how they might be used in treating pitching injuries, and why they might not be helpful at all in a pitcher's return to the mound. Next, Angel describes the importance of elbow angle at max external rotation, and how an incorrect angle can create shoulder problems, such as in the case of Tyson Ross. Finally, using Matt Harvey as an example, Angel explains what a pitching coach means by "pushing the ball" and how the back leg affects command.