We are only as good as our 'base of support' because the body works from the ground/bottom, up to counter the pull of gravity- especially noticeable in climbing. To be efficient in countering these effects of gravity, our posture (core) needs to be in a position that can produce downward force that is perpendicular to the 'ground'. If you are smearing on a vertical wall- your shin has to be at a particular angle between your foot (base) and your center of mass to produce downward force which will hold you 'up'. If that shin angle changes, you will slip in the direction that it gives to.
Concepts behind these exercises
'Feeling' and sensation based learning.
'Project' because these exercises you will figure out more by feeling through them on your own, as opposed to me telling exactly how to go about them. However, as you progress I will add some detail and complexity.