Midwif will likely have a breakthrough when she connects her pelvis (hips) to the torso. John and I both had this breakthrough as a result of the on snow PMTS drills and dryland movements/stretching. I needed alot of dryland work.
Josh, regarding the need for a flexible body. Age plays a role here. I have to stretch daily or I begin to tighten up to the point that CA/CB is very difficult to achieve on skis.
Agree that anyone that does the PMTS drills for CA and CB will have a major breakthrough as both Max and I have had. I also agree that flexibility is a big issue with CA and CB. Hip flexibility is just as important as back flexibility. Unfortunately running a lot tightens up and eventually locks up all hip flexibility. It took me about a year to gain that flexibility back (after running big mileage for over 20 years). Like Max I stretch mostly everyday and hip and back flexibility is a major focus.
I also agree that all high level skiing has quality CA and CB present. You just can't ski well at a very high level without it, especially off piste. I can also say that this is part of the reason I have no interest in attending a Clendenon camp. His CA in the videos is almost non existent and it is the same for the students. He may be teaching it and preaching it, but it just isn't in place in anyones skiing on the videos. I know I can't ski bumps without exaggerated CA and CB.
Lastly, I think there is a progression. In the PMTS world it just isn't worth much to work on other stuff until you can tip at a high level and initiate turns by tipping the LTE of the old stance ski. Typically it is tipping and flexing and CA and CB gets worked into the equation. But for someone that can tip and flex properly, CA and CB becomes the key to the next major breakthrough.