re: i need a baseball expert for a sec regarding a balk

If 2nd base is unoccupied with a runner on first then an inside move (the one you are talking about) is always a balk, regardless of whether the runner goes or not. The only acceptable move is a pick to first, or to first step back off the rubber then throw to second. The move you are talking about would be considered deceiving the runner. I say this assuming you are not in a league that has separate rules than 99% of other associations.