> the exact same things the sloppy player is doing, but you do it in time and in tune.

It depends on the level we look at it, but I think there is fundamental difference in what excellent (professional grade?)players are doing compared to "sloppy" ones.

It is not just done with more precision and care, they will usually have a different mental model of what they're doing, and the means to achieve the better result is also not linear. Good form will give good results, but it won't lead to a professional level result. You'll need to reinvent how you apply the theory to your exact body, the exact instrument in your hand, what you can do and can't and adjust from there.

That's where veteran players are still stellar while you'd assume they don't have the muscle and precision a younger player obviously has.

PS: I left aside the obvious: playing in time and in tune is one thing, conveying an emotion is another. It is considerably hard to move from the former to the latter.