[CecilOne]

Originally Posted by AtlUmpSteve

I don't think you are being very clear in your question. There are two possible answers, depending on what you mean.

If a runner leaves a base as (meaning at the same time as) the pitcher receives the ball in the circle, then that is a legal advance. And if off the base legally, the runner does get one stop or change of direction.

If a pitcher leaves a base after the pitcher controls the ball in the circle, then the cited 8.7-T(2) states the runner is out.

The difference is one of timing. Runners get an instant to determine that the pitcher does, in fact, have control in the circle before the lookback rule applies; the act of throwing it there doesn't make an instantaneous requirement on contact with the pitcher's glove. After all, the pitcher could miss or bobble the ball, and the ball remains in play during that time; so any play initiated at that instant (and before it has been determined the pitcher has control) is legal.

As an umpire, you should use the same timing urged for timing (force) plays. See the play, make sure there is a (controlled) catch, THEN call the out. If you call it on contact, you risk the double (out, no safe) call, as you never saw the completion of the play. Use that timing here; if the runner leaves the base before you judge control, then the runner left before the runner saw the ball in the pitcher's control in the circle, and that is legal. To call that runner out is treating the LBR as a "gotcha".

When teaching rec leagues and their coaches in clinics, I refer to that instant as a "decision moment". Every runner gets one as it applies to the LBR. If the decision moment happens while off a base and moving, then the runner still has one stop or change of direction available. If the decision moment happens while off a base and standing still, then that one first move within reaction time is the one and only direction available. If the decision moment happens while on a base and standing still, then leaving the base is a violation itself.

Well done !

And it is NOT a "gotcha" rule.