Steve A. have you done enough research to realize that the underweight object actually poses more of an injury risk than the overweight object? Also, important distinction is plyocare work vs. all-out weighted ball velocity throwing. The prior should preceed the latter to improve mechanics, strength, flexibility and reduce risk of injury. And there are many MLB guys using both plyocare and weighted balls even if their organization doesn't officially have it as part of their program. The reason why many have been slow adopters is because they don't want to be blamed and fired if a guy does get injured. If a pitcher(s) gets injured using a program like Driveline the Pitching Coach takes the fall, not the pitcher. Meanwhile many MLB guys are doing it on their own and seeing benefits. I agree there is much still to be learned about the subject, but to dismiss it out of hand as inherently dangerous is counterproductive to that learning and growth. We used to think the world was flat too.