As I relayed before, I concur with your thought that there is an involvement of the yi. And, we are speaking about Leon Hammer's hesitant pulse. There is another piece to this hesitant pulse and that is the notion of a lack of stomach qi, or moderation. 

A feature of the ideal pulse is that it has stomach qi (wei), spirit (shen), and root (gen).. The stomach qi causes the pulse to be moderate and represents the gu qi that comes slowly with harmony. Stomach qi is postnatal qi, it is the source of the postnatal qi and blood, and the transformation of the pulse is full. The spirit of the pulse is the stability of shape volume and temporal factors. Spirit depletion is signified by inconsistent comings and goings. When the pulse begins to flicker, develop arrhythmias and is easily changed in terms of shape and volume, then the spirit of the pulse is absent. There is no spirit if the pulse disappears.  The root is representative of the essence; it is the deep area of the organ depth and it is the proximal positions. The weird pulses all have a distinct absence of one or more of spirit, root or stomach qi.

This hesitant wave is not full. It virtually has no arrival nor departure. This is a concern in the area of stomach qi as opposed to spirit or root. 

Warmly,

Will

--
William R. Morris, PhD, DAOM, LAc

http://www.aoma.edu/