I agree that knowing the morph might help. Some morphs with spider in will be born without a wobble but develop one as they grow.
Is he/she aiming for your hand possibly? One of my babies missed the rat on the tongs (presumably because she aimed further back at my hand instead) and then sank her fangs into my other hand which happened to be holding the lid up =.= Of course she tried to constrict my wrist, no idea if she thought through on how to swallow my hand yet. Anyway I think the problem was that the rat was cooler than my hand, and she aimed for the warmer thing instead.
*Forgot to answer one of your questions. I feed all of my ball pythons frozen/thawed (except for the couple super stubborn ones that won't convert). All of the snakes I raised still constrict and kill their prey (again). I did purchase a larger female who was raised on frozen thawed and she will sometimes wrangle it and other times she will just slither up and eat it. So I guess it depends on the snake. Whenever I tong feed and try to shake the rat a little after they strike to imitate struggling, that way they constrict good for sure : )