Great thread here - this is something that a lot of high cappers, myself included, likely have issues with. I've written down about 10 things to try next time I go to the range.
I used to have the retracted trail elbow on the backswing that Erik demonstrated in the 5SK video. My eVolver instructor made that a priority for me last year, and I think I worked it out reasonably well. Since then I've been working to shallow out my swing and it's tough - my body just doesn't want to do these things...
Based on this thread, I've realized that I think I'm keeping my lead arm too close to my body in the downswing (going straight down, as that dude in the twitter video said). I think for slicers, we want to keep everything away from the ball to stop coming OTT, but it can be the wrong thing to do sometimes. I had huge issues in my backswing because of this before I started lessons.
I also really relate to the guys who have said that making contact from the proper A6 position is tough. I'm pretty coordinated, but it feels like an entirely new way of swinging. I'll shank a bunch of balls just starting from A6, which seems absurd to me. Just have to keep working though. Hopefully it's warm enough to hit the range tomorrow.