I think the forarm is utterly integral to the overall mechanic, without it you won’t be shredding to say the least with this style. You’re not going to be using your shoulder rotation to track the stings, the leaver is so accentuated it’s uncontrollable. I’m sure it’s used, no doubt, but same for the forarm, and even more so as it’s a second degree less if you understand, it’s one joint out of the picture. When I look at Zakk, I see major forarm rotation, even tho it’s bending into other movements. Perhaps I need to practice it more, tho the rotor cuff n pec are not easy to control, I really don’t see how you can do that combo and be as accurate as zakk is without forarm rotation facilitating the entire thing. You can’t be tense when soloing, you need to be loose, the rotor cuff pec elbow move is… at least not in my move set right now, I’m going to practice it because I can feel it… but The forarm rotation literally gives you a high definition control without doing that…
I don’t think either joints have enough fine motor movement to be useful for anything else than tracking, so as you already said there is an extra movement, think its the forarm.
You can see his veins on his forarm going back n fourth