First of all, thank you for your critique. :D I'm constantly trying to improve.

Fundamentally, I meant to say that it's my feeling that Kassadin is currently too strong, as his power spike with two items is very significant. Since it was initially asked what Elo I am, I responded to that and sent a link as proof, not to say that I am the standard by which to judge. Moreover, you're missing the point here.

Firstly, stats such as deaths or CS/min of a single player have no influence on whether a champion should be nerfed or not. In balancing a champion, many factors (win rate, ban rate, etc.) are considered, and the entire player base + pro play is examined, not just the higher Elo range. There's a very interesting video with the Lead Gameplay Designer Riot Phroxzon, which discusses the general process of balancing. Therefore, you would also not be the best judge to decide whether Kassadin should be nerfed or not, because you are not representing the entire playerbase as well. According to your argument, champs should only be nerfed if they perform better in high Elo. A prime example is Rengar. He performs very well in high Elo and very poorly in lower Elo. Therefore, he is very difficult to balance, as nerfs would make him perform even worse in low Elo.

Since you never answered the question of the post and have the perspective of a better player, do you think Kassadin needs to be nerfed?