OBR Balk where does it say this?

[bob jenkins]

This rule is the same in all codes. The NCAA rule has the "best" description:

(1) The pitcher, while touching the pitcher’s rubber, must step toward
the base, preceding or simultaneous with any move toward that
base. The pitcher is committed, upon raising the lead leg, to throw
to the base being faced, to second base or to the plate. When throwing
or feinting a throw to a base not being faced, the pitcher must
step immediately, directly and gain ground toward that base.

(end of quote)

IT all hinges on "raising the lead leg". If the "raising" is "toward the balance point" then the above applies. If it's just enough so the spikes clear the ground and is simultaneously accompanied by a hip rotation toward first, then the move is legal.