Basically, you’re not going to be able to squat very well with your feet straight until your ankle, foot, and hip mobility (not to mention your understanding of and ability to apply good squat mechanics) allow it.

This is why the FMS uses a parallel stance when assessing the deep squat: it makes the invisible visible. It’s much more difficult to compensate for missing ranges of motion and inadequate stability.

I think what Kelly Starrett is preaching, as far as squat stance goes, is that most athletes should seek to earn a parallel squat stance, and use that stance for the majority of their training in that motor pattern (since it should have better transfer to skills like jumping and landing, running, etc). But I think that, until that parallel stance becomes available to you, you need to choose a foot position that will allow you to train your squat, train it well, and not result in further compensation (or, God forbid, pain).

I still feel that, until you learn to approach your actual training in the squat with the attitude that THIS is the core of the solution, your gains in mobility will occur more slowly than they need to.

A big part of this whole thing that I’m not sure you’re grasping (judging from the post that started this thread) is that mobility and motor control are both very interconnected aspects of athletic movement and position. Mobility problems and motor control problems feed into one another, such that focusing too much on restoring one aspect of the movement may result in short term improvement, but that quickly disappears as the discrepancy in the other aspect continues to reinforce the old, dysfunctional condition.

It sounds like you are becoming very much in tune with where you are lacking mobility, but you have to become just as focused in how you approach training the squat itself. You need to understand how feeding more mobility into your ankles will affect your squat, do it, and then apply it deliberately.