Frozen Leg Balk

[Fritz]

Need some help resolving a discussion my partner and I had last night.

LHP, R1, OBR; pitcher lifts his front leg straight up and stops, holding for a couple of counts to freeze the runner, then continues toward home (good balance skills). I'm BU and immediately call Balk. DC comes out to ask for an explanation and I state the pitcher must make a continuous motion in delivering a pitch. He says it can't be a balk because he teaches all his LHPs that move as a way to hold the runner close (I'm still looking for that exception in the rule book, the one that cancels a balk if the coach teaches his players an illegal move!).

Anyway, he goes back and game progresses without incident. After the game, my partner and I debate why even do the frozen leg manuever if by doing so, it forces you to step toward the base to pick off the runner. Seems like as soon as the runner sees the stop, he should immediately head back to the bag ahead of the throw and wait for the balk call when the pitcher goes ahead and throws home.

We went through both FED and OBR rule books but couldn't find a specific reference to the freeze move, just the citations about an uninterrupted move associated with a delivery of the pitch.

Comments/assistance?