For USA its a rule change that allows any back step, so there could be some inexperience there. But the umps should be going to the training and learning the rule changes. High School is even more restrictive. In HS, the step back has to be completed before the hands are brought together. [Reading from the 2015 HS book] In USA, the step back has to be completed before the hands are separated.Thanks! I saw a pitcher whose step back started right when she split her hands. Illegal pitch wasn’t being called.