Leadbetter's A swing | Golf Monthly

I'm not an A swing advocate or an advocate of any guru, however in Ko instance the only reason the changes would have been made is she asked for his help and accepted the choices, nobody has a coach or his opinion forced on them.

Golf channel did a good comparison video where they had Ko side by side in her swing before Leadbetter, with Leadbetter and post his era. She was actually shallower on her AoA with Leadbetter than she was in her before and afters, maybe that's why she chose him originally but found it wasn't for her, bit like Tiger and Foley, he liked the idea but when in practise it didn't suit, but for others it will.

As for the A swing itself from what I've seen and read it doesn't create a steep AoA it's designed for the simplest and shortest movement on way back whilst clubhead still travels furthest distance whilst this shows a steeper backswing, it actually is designed to shallow the AoA on the downswing, much like Sergio does in a way quick pick up and drops it inside.

This is probably why the OP finds it better with his shoulder injury there is less stress on his shoulder with the A swing as it creates a different path on the shoulder turn