That is an excellent point, and there are other aspects of muscle fiber too, whether it is flexible and stretchable or tight, and it can vary from muscle to muscle. When I was dancing I could sit and open my legs out to the side to a very wide angle, but I could not really stretch hamstrings; I could only do splits by stretching the front of the other hip.
I agree as for Zabaleta’s playing, it was very fast and rather light. Not a great tone quality. As for your speed limits, it has a lot to do with practice