The pitch velocity gone up so much mostly by the development of better training and clearer communication within the baseball community that velocity is so valued. People like Tom House, Eric Cressey, Kyle Boddy, and Ron Wolforth have all pushed the edge and dedicated careers to research on what makes the ultimate pitcher. Pitchers are getting bigger, faster and stronger, and pushing their bodies in the weight room as well as with weighted ball throwing. All of this has created a faster, more powerful game for pitchers on the mound today.