The problem with building Yi tanky is what you put in resis/hp, he lacks in damage, and Yi was created to come out of nowhere and start smacking the crap out of champions. Another problem is that even if Yi were to be built tanky, there are a many great champions that can CC him and pretty much stop him in his tracks (even if he's used his ult). I think as Yi, you need to get a few kills under your belt to become a carry, otherwise you can try your best to come in last and hopefully the enemy team used all their CC, or you can backdoor. Yi jungle can work, but I've seen many, if not all, the Yi's in season 3 go mid.
