Posted by: Jack Mankin (MrBatspeed@aol.com) on Tue Jun 3 20:32:30 2008

Hi JLB

Your interpretation of the video is right on the money. It pertains to my present study of why the swing of many good college draft prospects produce slugging percentages far below those of equally gifted athletes. The inefficiencies found in their swing mechanics is rooted in a bio-mechanical principle I find very useful in motion analysis. It states, “A ballistic motion, once initiated, produces trajectories that can only be changed at its margins.”

As it pertains to the baseball swing, the principle basically means that forces applied to the bat during initiation produces trajectories of the bat, limbs and torso that remain basically on auto-pilot through the balance of the swing.

Without pressure sensors on the handle, we cannot see the forces being applied during initiation. However, plotting the trajectories of the bat’s angular displacement rate in relationship to the trajectories of the batter’s elbows, forearms and shoulders clearly shows the difference between batters who generate great bat speed and those that exhibit inefficiencies. This is why during initiation, I emphasize the importance of envisioning the rearward acceleration of the bat and the mechanics that produces it.

How, or if, these principles are taught to a student depends on the batter’s stage of development and the coaches understanding of the forces applied to the bat that induces its’ angular displacement rate. The better working knowledge a coach has of these forces, the better he can understand and recognize the mechanics that most efficiently produce them.

Jack Mankin