Riot, please show us that you have learned from past mistakes.
Remember last Worlds? Mordekaiser 98 (or so) % ban rate? Juggernauts dominating every game? All stemming from a considerable rework that drastically changed the landscape of the game, released right before Worlds.
And now you're releasing a completely reworked champion on the very same patch that Worlds is going to be played on. This means you're going to be unleashing a completely unbalanced (PBE and internal playtesting are not such great places to get a good read on balance) and potentially buggy (PBE and internal playtesting aren't perfect at catching bugs either) champion into the biggest League event of the year. This problem is exacerbated by the fact that the Yorick rework introduces a few unique mechanics for which we've yet to establish a good standard of balance.
Riot, Worlds is not a good place to introduce a fresh new champion to the world; at least, not in competitive matches. The best case scenario, that Yorick is well-balanced and bug-free, is not only the least likely but also still has its issues: Your pro players will have a limited amount of time to prepare for this new champion as people work on finding the optimal way to build and play him. And then there's the more likely scenarios. The first, that Yorick is drastically underpowered and therefore ignored, is relatively harmless. But the worst cases -- the Juggernaut case, a buggy mess, or both -- can potentially be disastrous for both the players and the spectators.
Riot, I urge you to either devote a hotfix patch to at least attempting to balance Yorick before Worlds, or, preferably, disable the reworked Yorick for this event. I doubt anyone wants to see another repeat of last year's Worlds.