The piano action physically disconnects the hammer from the key after you press it. Here's a diagram: https://en.wikipedia.org/wiki/Action_(piano)#/media/File:

The piano action physically disconnects the hammer from the key after you press it. Here's a diagram: https://en.wikipedia.org/wiki/Action_(piano)#/media/File:Fortepian_-_mechanizm_angielski.svg https://en.wikipedia.org/wiki/Action_(piano)#/media/File:For... All the complexity you mention only affects how the repetition lever (part 9) briefly bumps against the hammer shank (part 8). The only information this imparts to the hammer is velocity, and once it happens there's no more contact until the hammer falls back down. The hammer can't somehow remember what caused it to travel at a specific velocity and strike the string differently. There's only a single degree of freedom in its movement. What you perceive as "a huge amount of tonal variation" is mostly note timing.