Re: Quarterback Ball Velocity at NFL Combine 2008-2014
Velocity can certianly change, but over trying in velocity based events typically leads to a reduction in performance. The key is to learn to increase the primary muscles ability to create tension (specifically explosive strength as you have a limited time to apply force) and motor control to properly activate and reactive the appropriate muscles. Elite athletes can just do this naturally, this why they often look effortless when performing.
It's interesting, this bleeding of tension into other muscles actually helps strength based event, for example trying to squeeze the bar as hard as possible when benching or dead lifting.