Effective Velocity (EV) is the study of pitch speed and how location changes the reaction time of the hitter. Each different location creates a corresponding “100% On Time Contact Point”.
When a pitch at 90 MPH is inside or outside, the speed “Effectively” changes because the hitter has to hit the ball earlier or later as though the pitch gained or lost speed. So, in essence, the pitch location has caused the hitter to gain or lose reaction time. This is not just ‘Perceived’ speed, this is actual reaction time gained or lost due to location changes. In other words, EV is the ‘True Reactionary’ speed of a pitch. Think of it as ‘Location Adjusted Velocity’, where the speed is adjusted based on how much time the hitter has to react to a given location.
For every 6″ inches that the ball changes laterally, there is a little less than 3 MPH gained or lost, at 90 MPH of pitch speed. EV is like time management – only for reaction time. Bottom line in an at bat, whoever understands how timing works will win most of the battles.
The graphic shows the various levels of speed changes within the strike zone and ‘Pressure Zone’ (the 6″ area surrounding the strike zone). The closer to the hitter and more elevated, the faster the pitch gets (Red) and the more away and down (Blue) the more time the hitter has to react. Speed or Velocity is very relative.