Having a champ with a way to disrupt his Meditate doesn't help if the AP Yi has even half a brain. They get to farm/poke with literally no risk since he's untargettable, and if you manage to get him low he'll just hide under his turret to meditate so you can't knock him out of it. It really takes no skill to hit Q and get 100 gold every time you do, and as soon as you get Ionian Boots and Morellonomicon you can do it every 6 seconds (about every 4.5 seconds by the time he's done being untargettable). His poke/harass isn't skill based, just total luck, so there's no way to predict or avoid it, it just hits you sometimes and sometimes doesn't. The only way to totally avoid his harass is to be out of the XP zone in lane, which only makes you lose harder. I honestly think they're going to have to nerf him further in order to bring him in line as an AP mid.