When does a RHP commit?

[DownTownTonyBrown]

Pitcher is in his stretch. He picks up his non-pivot foot and has begun his habitual motion leaning back directly away from home plate - as described in 7-2-4d.

In the discussion so far, this commits the pitcher to a delivery to home. Have I misunderstood your comments?

My question is then what is the purpose of 7-2-4f?

Rule 7-2-4f: Failing to pich to the batter when the entire non-pivot foot passes behind the perpendicular plane of the back edge of the pitcher's plate, except when feinting or throwing to second base in an attempt to put out a runner.

Hasn't the pitcher commited himself to throwing home long before his non-pivot foot crosses the back of the rubber? (Some pitchers never cross it during their regular delivery.)

I regularly see Right Handed pitchers lean away from home plate with non-pivot foot in the air and then their first forward motion (before their hands separate) is a twist, step and movement toward 1st, with a throw. Should this be called a balk?