I agree with the leaves of the TGY varietal being thicker than most of other of varietal from Anxi. However, my sources on Chinese tea tells me that the level of fermentation (called oxidization in the west) has always been around 40%. The difference between the TGY that we are seeing now and the one that was produced a couple of decades ago is in the baking stage. The TGY is very lightly baked nowadays.
SEb