Even on the tlm serve video someone commented how the biggest problem is how rigid his upper body was.Look how Nadal’s racket follows through all the way wrapping around his back even on very slow forehands at the beginning. What level of looseness does it take, man?!
Post #600 by the way.
Racquet sport techniques are generally counterintuitive which is why a lot of rec players fail in emulating higher level players. A not too tight grip and relaxed body lends to a harder shot.