Undershape Motion

I learned how an undershape ends with a forward feeling on the upswing before turning the hand around. The concept of an undershape can exist between as few as two notes, such as two chords in the left hand.
Shaping, as taught in modern piano technique, is inexorably linked to phrasing and singing tone. Shaping is the continuous motion between the notes that physically link the musical thought process.

Shaping is also an indispensable tool in the transition from retraining movements to functional playing along with tone production. This is because shaping fuses

1. rotation,
2. in and out, and the
3. walking hand and arm

together. Rotation and the walking hand and arm become minimized, and playing begins to look and feel "natural", despite the efforts of retraining.
The wooden tone that can accompany large retraining movements transforms itself into "musical" phrasing. Thus, Fraser's criticism that rotation on individual notes works "directly against any sense of phrase" is likely to have been based on observing the retraining of pianists prior to adding shaping.
Through shaping, the experience of playing is at the fingertips, with the feeling of the key "growing out of the fingers" . A common phase is to "fall in love with shaping" usually at the expense of other movements such as rotation, and the in and out. Thus, the introduction of shaping is often deferred until the basics are solidified, even if that necessitates a temporary separation from "musical" elements such as tone production.