Whenever I look at Lolking's winrates for champions the last 2 years, I always see Jayce below 47%. He's a difficult champion with a lot of weaknesses. There's a guy that has done a 100 games to diamond with Jayce. He failed it, while with Yasuo, Tryndamere and Wukong he succeeded easily. (streamer: n3ac3y). Of course one subject is not enough. But he has too many weaknesses, can lose easily when 5/0. Gets outscaled by a lot of team comps, is useless for his team a lot of the time.
/.end rant Kappa