Bustamove
One continuous motion with good timing in arm-swing is a good way to describe movement.
I would also like to add that armslots can be different and have to be discovered by each individual because you want to find what's natural and works without thinking about it too much. Armslot could be HTQ LTQ OT which depends on each, his own. If a pitcher is a natural three-quarter slot guy and is trying to get elbow up too high by using over-top delivery, he may be restricting arm-action thus effecting arm-speed, timing in unlocking components in delivery and a host of other key factors.
My advice would be too make sure the pitching hand brushes side of back-leg and show the ball to the sky(CF) in arm-swing all in one continuous motion. Teaching Cue: Ball to the side then show it to to sky. This will help develop the timing and help keep your arm in a natural slot in arm-swing back then forward. Hope this helps! It's more difficult to describe in words than in person but the last pitcher I worked with about what we are talking about here is throwing mid 90s now but also has professional instructors who have further honed his skills
Peace, Shep