I think the drag of the back foot is a symptom not a cause of mechanical issues that can lead to a decrease in velocity.
If you are an over the top thrower, foot drag would implicate a too soft of a front foot landing. This would case the hips to drift forward instead of pivoting on a solid base. Slow hip rotation = slower release velocity.
If you throw 3/4 to sidearm the foot will naturally stay in contact with the ground longer as it travels to side more than up as a result of the follow through. I've seen tracks of the pushoff foot from a submarine thrower go in a large arc of over three feet. He was a 90+mph minor league pitcher in the Giant's system.
Steve
