Thanks again!  I think my problems are caused a lot by what you said
about my “pelvis not completing its rotation and “‘getting left
behind.'”  I’m beginning to notice that trying to flex my lumbar spine or round my back is providing me with some more stability… as long as i can maintain anything else.  I noticed my left leg, which has been more stable due a pelvic rotation, was able to step up better because hip flexion wasn’t blocked.  But putting my right leg on the bench, I think the femur is running into the hip; he talks about this in

http://www.mobilitywod.com/2012/02/why-sitting-wrecks-your-mad-hip-action/
https://www.youtube.com/watch?v=ZkzFT6rRMhQ

and a few other videos.

So if I round my back more, this would allow the pelvis to complete the rotation and the femur can clear the hip.  Of course this is a tense and scary thought, because we are constantly told to not round our backs… but I think if I’m stuck in extension, then going to neutral will feel like rounding my back.  It’s also a matter of glute activation I think as well.  Unfortunately, I’ve spent months doing glute activation, obsessing over correct form, and still not getting the mind-muscle connection.  This is what makes getting into a good position so hard… the first step is squeeze the glutes, and in all the videos I see, they just say squeeze the glutes.  But even after activation drills, I may squeeze my glutes, but other times I may be contracting something else… addutuctor, TFL, an external rotator… no queues allow me to consistently do it correctly.  For example, if I try to screw my feet into the ground and/or turn my knees out, sometimes I end up just trying to do this from the tibia.  In addition, all this concentration ends up getting me so tense, so it’s a perpetual cycle of stress and frustration.

Trying to crunch up and round my back more while supine kind of helped with glute bridging today, so if I try to take that approach, hopefully I’ll see some results… I suppose I may have been trying to flatten my back with only my TVA and not my rectus in the the recent past, perhaps because of the emphasis I would hear about the need to strengthen the deep abdominals not going into trunk flexion.  Of course, crunching up gets me all screwy with my neck… I’m always trying to look to make sure my form is correct, and if i realize it and try to relax the neck, it just ends up tilting backwards.  Trying to tuck my chin ends up being just like trying to contract the glutes… sometimes I’m using the right muscles, other times I’m just firing different stuff around the neck.

The other part is distinguishing lumbar spine and thoracic spine movement, since chest out for years was probably just more lumbar extension, which coaches weren’t correcting.  So much of this is mental, because when it clicks, it clicks and I perform great.  I just wish there was a fool-proof way for me get into the right position every single time, just like the bracing sequence seems to do for everyone else.  This way I’d be able to practice these movement patterns correct every time.  I already think about my posture 24/7, and I do devote time to stabilization exercises.  So I continue to look through mwods, and now the mwod pro videos, to see if I can find anything new that will help my brain click.