I think I understand how the updated Balance skill works now. You are given a percentage of the type of cards that will go in your starting hand. So let's say you have a 20 card deck with 15 monsters and 5 spells. That means you have a 75% chance of obtaining a monster card and a 25% chance of obtaining a spell card. Unlike the old balance skill, where this setup gives you 100% chance of having 3 monster cards and 100% chance of having 1 spell card, this change means you have more randomness and your deck will no longer be as consistent as it used to.
That kinda sucks tbh. Haha
Source from Reddit tested 7/7/6 is the ratio that can bring you somewhat closest to the new balance consistency. Monster/Spell/Trap ratio of 7/7/6 can get you either 2 monster 1 spell 1 trap or 1 monster 2 spell 1 trap
I've used a balanced fusion deck of 15 monsters and 5 spells and pulled a full hand of monster every now and then. I don't really have the time to write things down, but that's the conclusion I came to.
Multiple tests I did showed high level of randomness for 4th card, lower for 3rd card, minimal for 2nd card and almost non existent for 1st card. One would think that by running 14 monsters in a CA deck you would get one monster hand with a high chance of 2. However after about 39 duels got several hands of 1 monster and 3 spells. By 60+ got a full spell hand with a monster on the top of deck.
Considering that I just came to the ironic (but expected)conclusion that balance is now way too imbalanced to be trusted as an skill. I'd recommend it only for handless decks or similar stuff that play mixed monsters, spells and traps since it is almost guaranteed that you will get 1 monster at some point of the 1st or second turn (rarely).