A friend sent me an instagram post or some sort, of what looked like an elite junior getting coached. Maybe a 40s clip. Coach says, 'many people think spin comes from the legs', then demonstrates a high to low swing path, along with using legs to assist. Then he demonstrates a low to high brushing motion with wrist/forearm/shoulder. Then says, if you're legs are moving up, as your are brushing (up), you negate some of the brushing action, therefore, when you swing, I want you to picture a roof over your head as you swing, and do not poke your head through the roof. Then she hits some shots. Good ones.
My friend thought it was a bit counter intuitive. He had always assumed you need legs for spin.
I told my friend, maybe she had a slight head bob in her stroke ( we didn't see anything prior in the clip), and coach told her that to make her correct her habit subconsciously, because surely she had tons of leg drive in her strokes (which she did, elite junior legs).
Then, a member of TT was video reviewing my forehand, and mentioned that elite level players have a ton of separation between torso and lower body, perhaps not seen in practice swings, but is the source of great power. I thought to myself, well, i'm at best a 3.5, I have bigger things to worry about than separation for elite players.
Then today, I was practicing on my topspin pro at home. And I decided to adopt a strange stance to check out what this separation was all about. I would take it to the extreme. Both my feet would point straight at the net, and I would twist my shoulder 90 degrees. HOLY SHIT. Suddenly, I felt stretches in places I've never felt before. I could feel my leg "load". I felt (and saw) the racquet pass in front of my body. I saw the outside in swing path.
Then I thought back to the video. Then I wonder, if the legs are not really intended to provide a vertically driving force (in the forehand). Perhaps as a driver, the more useful energy they provide is rotational. Or forget even about moving the legs. Just release the shoulder/hip separation energy, and use the feet as an anchor (I kind of like this description, especially since my shot is floaty and inconsistent).
And now, I just remember another forum post mentioning that the reason my forehand is wack is that even though I have shoulder turn, the turn is not rooted anywhere, ie, the energy is already transferd to my front leg and the shoulder rotates in the followthrough.