JRutledge,
If I am picturing/understanding the situation correctly, the issue is whether or not it is legal for the pitcher's pivot foot to lose contact with the rubber prior to him releasing the pitch.
If that is the case, I would suggest that virtually ALL pitchers at ALL levels do this virtually every time they throw a pitch.
Some "drag" their pivot foot off the rubber as they land their stride foot and push off the rubber to deliver, some bring their foot into the air, e.g.:
You will never see an MLB, NCAA, or High School pitcher with his foot still in contact with the rubber at the time he releases the pitch.
If you're talking about something else, my apologies for interrupting.
JM