If you look at the foot and the sensory innervation of the skin underneath the foot, it arrives from or is the extension of the sciatic nerve. This nerve starts high in the posterior gluteal region, below (or above) the piriformis, runs through the medial en laterals hamstrings and runs behind the popliteus/calf. 

So stiffness in the places you targeted could desensitise distal to the extremities, so if the tissue is released you have better sensory awareness. 

Hope this answers your question.