I pretty much knew that you understand all of this stuff, despite differences in jargon. And I get where you're coming from--if a pitcher has a pronounced tendency to muscle up on the ball, coaching him to feel "rag loose" would usually be a step in the right direction. Presumably, no pitcher would take "rag-loose" literally, for more than about one attempt at a pitch.
Very well said!
The only point I quibble with is excepting the change-up from your discussion of how the fingers apply linear force and spin to the ball.
To summarize my experience, all pitches are thrown with as-near-to-identical body/arm speed as possible. FB obviously has most linear force applied because of the FB grip. The FB grip also allows for very high backspin rotational rates--in the neighborhood of 30 +/-10 revs per sec.
Quality curves are thrown to get even higher rotational rates, perhaps 40 +/-10 rps, of topspin. Because the i- and m-fingers are not directly behind the ball for breaking pitches, curves are considerably off-speed.
Change-ups are the most interesting (and least understood) pitch in some respects. My pitching mentor taught me that the highest quality varieties of change-up are all thrown with significant pre-set pronation of the hand/wrist/forearm. Whether you throw a C-change, O-change, or 3-finger "pitch-fork" change-up, the pronated change-up grip imparts screwball-like topspin and the fact that the fingers are not directly behind the ball takes considerable velocity off of the pitch. Pitchers who throw a change-up without a pronated grip are really throwing a mediocre FB, which usually will lack decent movement--because the spin is FB-like.