I am having a very bad time playing Yorick

I am yet to know the exact reason why I am not doing well playing Yorick now... Before I could beat most champions in top lane by playing him. Now it seems like most of them can actually outsustain and outtrade me if I try to play him. My last games with Yorick, I did so poorly that I stopped playing him.

As I said, I don't know the exact reason for this but I have some theories. The first is that, now that there is a mastery called "Grasp of the Undying" almost every top lane champion can have at least some level of sustain to compete with Yorick.

The second is that without mana potions, I tend to go OOM before I can do much, even with a Tear early game. Before, I could buy a Flask + 3 mana pots and outsustain and bully most champions by spamming ghouls. Now, I am forced to start with a otherwise I am doomed to become OOM.

The third is that this meta is very focused on early game, and even though Yorick technically has a good early game, he is forced to go with a late game oriented build (Tear + a bunch of other items that delay Yorick's tankyness a bit) which means that Yorick does not powerspike as well as other champions.

However I am not entirely sure of the reason for this, but since the pre-season 6, I am not having success with Yorick, while before I had. It seems like a combination of factors made Yorick a pretty weak pick for this season, even though he was always underplayed, but he was not always weak.