A car possesses more inertia (than its driver) because it weighs more. When it crashes, energy is transferred into the path of least resistence (driver) and accelerates the driver violently. This is why we have seatbelts. This is the same ideal behind pitching and hitting. The more mass and accelerative force behind the baseball - the faster and further it goes.
NEWTON'S FIRST LAW OF MOTION (LAW OF INERTIA)
Every object in a state of uniform motion remains in that state of motion until an external force is applied to it. For example, a baseball does not move until a pitcher applies force to it. Additionally, the more mass an object has, the more force required to move it (inertia).
NEWTON'S SECOND LAW OF MOTION
For every action, there is an equal and opposite reaction. Baseball requires an explosive energy transfer (not a uniform energy transfer). Therefore, according to physics, a balanced force must hold back this explosive energy to harness its accelerative potential (known as elasticity).
A balanced force requires two equal and opposite reactions to be equal in size, but opposite in direction. This is why deliveries and swings are optimized with athletic balance. Since balanced force requires energy to be counterbalanced, mechanical training contradicts physics' theorems because it trains one aspect of balance, not the entire balancing "act". Hence, VeloPRO.