1) He implies that practice is something to be less proud of than inherent ability to play pool. Life is all about making decisions to practice/pursue/play certain things over another.
The other thing is that few people have the willpower/dediction/stamina to devote time to activities that truly challenge them. Sure, I can play chopsticks on a piano, but beyond that I couldn't sit still. Yet, I don't hear a great musician and think, "They just practiced more than I did."
That's why certain activities are viewed with more respect. For example, being great at Modern Warfare 2 is not something that will win you much praise. People don't view it as taking much willpower to play a video game for hours on end. It's kind of like the default state of most people. But people will likely praise you for being great at math.
2) He also seems to think that inherent ability plays no role (I presume that 5% luck, is luck in the instance of the game, not luck being gifted at it). While practice is important. I suspect there is probably large variance in the initial condition of various people for various activities.
The only thing you can probably be confident of is that with good practice you will improve. But no guarantee that if you do more hours of practice than another person that you will be better.
Tracking something like this in class I suspect is more likely to actually teach kids that practice isn't sufficient. In fifth grade I spent many of hours trying to breakdance, and I never could do a headspin that friends of mine could do almost out the womb. I think I'd only be more discouraged to see how much time I wasted on it. Although looking back, it was worth it, and it strengthened my upper body for other activities. I just can't head spin for some reason.