The “great hands/smoothness” of a good SS is due to them always getting the right hop for every ball..which is not easy due to the myriad of different types of balls they get. For the most part that has nothing to do with athleticism.
I honestly have a hard time watching most SS play (especially younger ones) , including my kid a lot of the time, because I physically “feel” it when I can see they are going to get an in-between hop just from watching their footwork.It is like a PTSD thing
You can see an error coming long before the ball gets to an infielder sometimes. Even with decent fielders. I've always wondered how I could tell, but I think there's something about seeing many thousands of ground balls that your brain is processing the bad/mistimed footwork and you just know the ball is going to eat up the fielder.