Yorick Mid/ Yorick Support??

I've heard that Yorick mid is pretty strong. Why isn't he played very often then, even not in normals? And another question: couldn't yorick support be decent too? (maybe also rushing on a tear and buying gp10 aferwards) I mean, he has a slow, great early game harrass even without items, and his ultimate is also a great help for the ad carry, especially in late game when his poke begins to fade into nothing. so what du you think about it?