8th is unbalanced for the same reason that 7th was unbalanced: the army books. Except now not only are the books not even remotely written to the same standard, but none of them are actually written with the mechanics of 8th in mind - and I don't particularly believe skaven or beastmen actually were, especially the latter. The best example of why this is a problem are empire mortars and bret trebuchets, which cost nothing compared to how jacked up they suddenly became. The books weren't balanced before 8th, now they've been torqued further out of alignment by all the boosts which have not been reflected in any points or slot reevaluations.
Tomb Kings is going to be a very interesting release, if it's indeed next. Seeing how they repoint skeletons, now that fear is nothing and crumble is far inferior to steadfast mortal troops, and scullapults will be enlightening, and then of course TK will be the first book to actually be built to push a new rules system. I'm expecting a huge pile of myself
I don't know about that when O&G win tournaments there is an issue. 4 tournaments so far
O&G
warriors of chaos
Dark elves
Lizards
4 different armies and 2 of them not even top "5"
The problem is people not building all comers lists. Power scroll shadow win win. But on the other hand you might be on to something we need more time more tournaments more of everything to know for sure if something is over powered or not. All I have so far is 4 tournaments 4 different armies winning