Historically he has been played top lane, and what it turned into was Jayce simply losing out in a war of attrition, in addition to the fact that his mana hungry early game, in a meta focused around early plays, hurts his ability.
Jayce for awhile has been a champion completely based around how effective Black Cleaver and Manamune are. Right now, in general, poke is a wanting concept unless you have a nidalee or a good poking mid laner, neither of which are common, and on top of that, Jayce is commonly a glass cannon, and with black cleaver being a purely bruiser item meant for melees(In the past, when brutalizer was part of the build path, and BC gave more AD he was much better), and that his tear has to stack up, he is found wanting.
Something I would like to add also is that when assassins are popular, jayce is hard as hell to play reliably because he is very prone to getting one shot, because of his most common build paths.