So some new manifestations of instability but I think it's mostly that the stabilizer muscles in the front of my legs above the knee that used to be locked are live variables now, that's a degree of articulation I hadn't been expecting
Also something is happening in strips of my rear flanks from where the shoulderblades meet the armpits down to the hips
I think with the flatfooted style a lot of stuff on the front-facing side from the very top of the hipbones down through the top of the shin has been locked stiff. And I guess the shin itself carried that through a pretty locked ankle, so the whole thing was just driven by motive power from the back of the upper leg.
So really my being good with legs grappling on my back (back kicks, too!) at the dojo was just like that Down's guy with "retard strength": not using auxiliary muscles, we had to strengthen primary groups for regular use to the point they were extremely powerful
I would leg lock them and hold their whole torso rotation with one leg, and then go for bottom mount or upa for top or even just stay like that and tire them out with a leg free to fuck around with and neck hook them with