Does one foot have to contact or be in contact with the rubber at the start or at all times?
OBR states at all times, but it has become acceptable to lift and place the pivot foot or to start with the heel in contact with the leading edge of the rubber and to pivot from there. The outside edge of the pivot foot should be in contact with the leading edge during the lift, however, concessions will be made for mound conditions that prevent such contact.
I’ve always wondered how closely umps actually look at the foot contact with the rubber? Especially if there’s just one guy behind the plate. Most town and rec mounds are truly so poor that it’s inevitable a pitcher will come across one where keeping foot contact is impossible because they’re trying to pitch out of the Grand Canyon or something.
It has to be a really bad error for the pitcher to get called for a balk on the pivot.
You might want to take a close look at Don Larsen and his no-windup delivery. He didn’t even pivot, he just took a step and threw his strikes, as I recall.
I know one kid who would take full advantage of any one umpire games when pitching. He would place his foot at least 6-8 inches closer to home plate during his pivot from the wind up or set it down six inches closer to home during his stretch before coming to set. Impossible to see from behind the plate unless you are looking for it. When the mounds were really bad with the standard double-foxhole configuration, I would do the same thing so I wouldn’t have to stride into a ditch. When they called me on it, I would ask the umpire, “who gets in trouble if I break my ankle?” and that would result in the mound getting temporarily repaired. Otherwise only the pitchers can make modifications to the mound during a game.