https://www.ncbi.nlm.nih.gov/pubmed/27872403
"As pitching slightly underweight and overweight baseballs produces variations in kinematics without increased arm kinetics, these exercises seem reasonable for training pitchers. As flat-ground throwing produces increased shoulder internal rotation velocity and elbow varus torque, these exercises may be beneficial but may also be stressful and risky. Flat-ground holds with heavy balls should not be viewed as enhancing pitching biomechanics, but rather as hybrid exercises between throwing and resistance training."
25 subjects, 10 exercises, 3 trials = 750 trials total conducted on kinematics/kinetics. I can tell you from experience this is a giant pain in the butt and represents a very comprehensive look.
As for the conclusions of the study, I look forward to reading the full text in the near future before making any comments. Obviously the abstract looks good so far.