I suspect Parker was completely out of gas yesterday. I suspect Patty might have used her as a reliever if she thought she could go a couple of innings and if we had the lead. That wasn't the situation so it made more sense to let her rest.
Look at it this way - if you are in a winner take all situation, you want Parker as rested as possible to give yourself the best chance to win.
I think Paige would have headed in to pitch had we ever regained the lead in the last couple of innings. However, if we'd started Paige last night and lost, tonight would have been all over but the crying. It's going to be tough tonight but if our defense improves and Paige is a little more rested, we'll have a fighting chance.