What divides good and bad Malzahar player?

So my Bronze friend argues constantly how I'm bad in the game and only way I do decently in his opinion is by playing Malz, who needs no skills according to him. I do find playing him easy. As having 150k points, is it that I have just learned the champ somehow or is he really easy? Also as the title states, how does one make the line between good and bad Malzahar player?