Look back at his AAU tapes, if you can find longer ones (or ideally whole games), because the level of competition in AAU is a higher level than most high school games. AAU is like basically playing against HS all-star teams, or like JUCO level competition.
Another thing to look at is how he uses his body to get past people. Does he expose the ball too much? Does he use his hips or shoulders to get past the defender? (Good fundamentals translate to a higher level, generally speaking.)
He may not look "super quick" in these last few clips that Donna Ditota posted, but you have to remember that even in college, most PGs are not 6-6. He's going to have a size advantage in almost every game he plays at Syracuse.
Reading that he posted up smaller guys and scored on them at will is a great sign. If people try to play man against us, he'll probably still be able to do that, at least from time to time.
If you think back to Michael Carter-Williams' time with us, in his first year he seemed too gangly, and not all that fast, either. But he had great vision (which Copeland shares), he got up to the speed of the college game in year two, and then he was off to the pros (and became Rookie of the Year).