The National Pitching Association did an elaborate study to determine where and how a pitcher gets his velocity. For years, tradition has directed our thinking into believing any number of ideas including the "downward plane" and "pushing off the rubber" myths of generating velocity.
This study, however, looked at pitchers from Little League all the way to Big Leagues and measured linear and rotational velocities to find out the truth.
The results revealed that 79 - 80% of velocity is generated by rotational movement, otherwise known as torque or hip and shoulder rotation. This can be achieved by throwing from two knees at approximately a 45 degree angle to the target. (This takes the legs out of the equation and is all torso-related).
The remainding 20-21% comes from linear movement, achieved at leg-lift. The thing that comes into question for a pitcher, then, is what he is doing to maximize both kinds of movement and velocity.
Take into consideration these two photos. Both are at leg-lift and both are major league pitchers. While the rhp is "using" his momentum to maximize linear velocity, allowing his body to generate velocity toward the plate, the lhp has stopped his momentum and won't generate as much as he could. In other words, one pitcher is using his 20% while the other is not.
I have received many phone calls over the years from coaches and parents who have wanted to know why pitchers can't throw as hard from the mound as they can from the outfield, or infield. The answer is the additional linear momentum/velocity position players get by never interupting momentum as they throw. In other words, position players never "pause at the top" and lose this valuable momentum.
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