Here I will be analyzing Rick Nash's pre-NHL career to help show why he is an enigma/under-achiever.
Yes, he scores goals. But even with his constant 30+ goal seasons, he never had that one huge goal scoring year, even if he seems to have all the skills for it. He also never put up great point totals. In nine seasons, he has only broken 70 points in a season once. So the question is could have you predicted this when he was drafted. I think so.
He put up great goal and point totals as a 17 year old in his first season in the OHL. Then, as an 18 year old, he stagnated as he managed basically the same goal and point totals as the year before, which is his first missed milestone and bad sign. Nash really should have seen his goal totals push past 40 goals and his point totals reach around 100 if things were going well.
In addition, for a guy who was being touted as the number 1 overall pick, he had a weak World Junior Under 20 Tournament. He only registered a measly 1 goal (for a renowned goal scorer, this is bad) and three points in seven games. He should have been one of the dominant players in the tournament if he really was an elite player who was going to go on to great things in the NHL.
To me, all this suggests that he has talent, but that he has consistency issues that will hinder him at the NHL level.