nopachunts wroteWhere's the BU in your screen shots? If they are using a three man crew, shouldn't U1 be closer to 1B shoulder of F4? Trying to learn softball mechanics.
Although that is an unrelated to the OP, the mechanics by this crew are not standard NFHS (the first play had U3 "rotating home" when U1 chased; there was another play where U1 turned and looked, but didn't chase).
The pre-pitch positioning for U1 with a runner on second is to use either shoulder of F4, where I prefer to use the right shoulder. Your responsibilities (in part) is to cover the pick off at second, and cover first/second if U3 does not chase. Where you choose to position yourself is where you are comfortable.