Touch is perhaps the most elusive skill involved in piano playing. It cannot really be taught because it reflects the most intimate connection between the player's inner ear and the tiniest nerve endings in the skin of each finger.
I have been knocked down by the touch of a few pianists in my lifetime. Could I figure out what they did? Not really. Could I figure out what I wasn't doing? To a certain extent, I could.
At one point I lost sensation in my fingertips for a few months. During those months I was performing regularly and also recording those performances out of which two CDs were ultimately produced: Haydn / Bartok and Piano Works of Joseph Haydn. During the performances I was unable to hear soft sounds : I couldn't feel the keys, therefore I couldn't hear them!
Yet the sounds are all there on the recording. So intimate is the connection.