They have a good base for skills, they just need to buff the skills some to make them feel better. Passive could benefit from making graves every 10/8/6 seconds and be affected by CDR, this way he can almost always get some up during or before a teamfight in the jungle or pits. Q healing really needs to have some kind of scaling, either with max health or AD in some way. W could get a Poppy style anti dash effect for 1-4 seconds to create an interesting and denying skill to many of the champions in the game. E looks like it needs some either scaling on the movespeed bonus or some way of making the ghouls that land attacks increase the slow even more, that way landing it with ghouls up is better. R seems good but does not appear to have nearly enough pushing strength on it's own, it gets focused by the tower too quickly and taken down too fast.
Long story short, the skills are fair right now, but they all lack scaling stats which will end up keeping him down more than anything else. His old kit scaled extremely well actually, movespeed boost on Q was fast, slow on W was sufficient to get in range for an auto unless the enemy dashed away, E heal is what made him be able to survive focus for more than 4 seconds, of course his Ult let him duel many champs and gave him a non selfish Ult for the team.
If they want to see Yorick succeed as a rework they will need to buff him in a manner that feels consistent with his lore. From what I have read on the PBE boards his AI for ghouls and Maiden will be better for coming from the jungle with his walkers, but less useful if you are in lane with them and want them to go to another lane.
The issue is they do not want is to hear a huge outcry about his presence in lane from having tons of ghouls dropping on the enemy constantly. They are concerned with making him too strong in general, maybe so intimidated by it that they are trying to check the issues before it goes live. I feel that is not really the way to handle this champion, but I hope it goes live a little less strong so I can just keep playing him without seeing him get banned or picked by everyone and their brother. I main Yorick, and will likely continue to do so, even if he is not ridiculously powerful.