The more explanations you hear sooner or later you will find one that you understand better than the rest. This one helps me.
I highlighted two sections in bold print.
David, let me make a suggestion: It's easy to overcomplicate things. I remember when Karel started on the mobilisers and stabilisers thing, late in the Neijia List days. It's a grand theory, but he'd have been better off thinking a bit more about making gravity his friend. So would you. "Making gravity your friend" is the modern, "let's-don't-talk-about-ki" way of describing the force manipulations, etc., that have been discussed, diagrammed, etc., already.
The "fascia" stuff is part of all that, but not in the way Karel's unique theory describes. Here's the old traditional way of describing the interrelationship, but if you don't know what it means it may not be very helpful:
(Extracted from the "Yi Jin Jing")
A man's body consists of the entrails, spirit, and virility internally; and
of the arms, legs, tendons, bones, and flesh externally. For example,
tendons and bones are outside the entrails, flesh is outside the tendons and
bones. Blood vessels are inside the flesh. But Qi is the dominant factor
for one's physical movement. Thus the secret for cultivating one's physical
and mental capabilities is to improve one's Qi and to invigorate one's blood
circulation. One's spirit and virility are invisible or untouchable, but
one's tendons, bones, and flesh are substantial. To cultivate internal
spirit and virility, one must start doing the practice of the substantial
parts of his body first. Therefore, one should not practice the invisible
and untouchable spirit and virility only or just practice the tendons,
bones, and flesh. The practice of one's body must go along with the
practice of one's spirit and virility. Because of this, the practice of
internal work should be done in thie sequence: Qi, membrane, tendon.
While the practice of the tendon is easy, the practice of the membrane is
difficult, and the practice of Qi is more difficult. Students must start
practicing from Qi first in order to keep Qi moving everywhere within their
bodies. The membrane will stretch automatically at the place where Qi
reaches and be as strong as tendons. If one practices tendons without doing
the practice of the membrane, the membrane will be weak. If he practices
membrane without doing the practice of Qi, his membrane and tendons will not
stretch. If he practices Qi without doing the practice of the tendon and
membrane, the Qi will not circulate smoothly within his body and his tendons
will not be strong. To achieve the practice of internal work, one must keep
doing it until his tendons and membranes stretch and become strong.
Otherwise it would be like plants on the ground without dirt.
If you do know what it means, it's got very little to do with mobilisers and stabilisers.
Incidentally, Tohei's soft/relaxed approach (and that was undoubtedly Ueshiba's approach, but Ueshiba left less specifics than Tohei has) is better for developing this part, IMO, than some of the "harder" approaches.