I wonder how Makneto would fair in SF4 due to the wicked damage scaling after a dizzy.
Anyway to answer the original poster’s question. A good player knows how to adapt during a match. They have most of the fundamentals down like basic matchup knowledge, execution, character reliable combos (bnbs), and their characters best punishers. What separates a good player from a marque pro player is probably experience and their ability to stay calm under pressure.
A good player may know basic stuff to look out for, but may not be able to recongnize certain tricks. Or if they are facing a major loss they can’t find a way to come back. What I like about people like Sanford, Justin Wong, Daigo, Nuki, and Kuroda is their insane ability to put it all together and make a comeback. And they seem to know all of their options in a given matchup like the back of their hand.
A really really good player makes it hard for you to get a win off of them. They really make you work for your damage instead of having it served up on a platter like a scrub would. A good pro player know how to put you into a damaging predicament and stay out of one themselves.