Well my posting the baseball bat video is specifically to show that oftentimes in impact events, we can't assume that normally-stiff objects will stay stiff. We usually assume that wood is pretty stiff because the forces we exert on them are relatively low. The finger can strike the key very quickly, however, causing the key (and subsequent action all the way to the hammer, and ultimately the string) to flex in various ways that we don't see because it goes by too quickly. The question is whether or not this can actually produce a different tone.
I admittedly only briefly skimmed Ortmann's thing, but in it he makes a bunch of assumptions that waves all this away. For example, he says that "The three fundamental properties of a moving body, as we have seen, are mass, direction, and speed. For any one key the mass is fixed; the direction for all keys is fixed; the only variable remaining is speed. Consequently, any differences of effect of touch upon key -movement must be differences in speed. There is no other variable." But when you assume that the only relevant properties of a moving body are its mass, direction, and speed, then you are ignoring all other properties such as internal vibrations, flexing, compression, etc. He didn't prove that these factors don't have any impact, so much as that he assumed a simpler model of the action which inherently does not account for them. He's making a rigid body assumption when the discussion is about whether or not that can properly apply here.
A more accurate way would be to assume that the flexing, etc. could affect how the hammer hits the string (i.e. have them as part of the model) and then show that regardless of (for example) how the finger accelerates the key, its effect on the string is negligible (basically zero). I think for this thread the discussion is more about whether or not tone is independent of volume, i.e. if a single key, played at the same volume but differently (i.e. different hand positions, curved or straight fingers, etc.) can result in different vibrations and overtones on the piano. I am assuming that "tone" here is really the spectrum of frequencies and relative intensities of different frequencies when a key is pressed.
There's more here that I'd like to post about but I'll get around to them later. Regarding the damper thing, I was using the damper during the piano lesson, i.e. I'd have it down prior to beginning Chopin's FI, then I would hit the G# octave from far above the keys and let my hand bounce off. The piano teacher said it'd be better (better tone, not louder/quieter) if I started with my hands on the keys and pressed into them as if I were trying to make the other end of the piano vibrate. He said it would sound much better that way.
P.S. With regards to the original post, I'd like to point out that it's possible that when you started playing less loud, you were also doing something else that ended up producing a different tone (less tense, hands staying closer to the keys, etc.) and your piano teacher was picking up on that rather than the volume.
Topic: "Tone" doesn't exist.