Sorry to say this but I would really consider a relook into the balance changes regarding the Amagi and Iowa in particular. Myself and many others in numerous comments, posts on reddit and other sources have said the rudder,health and damage nerfs to the amagi are not needed as the ship wasn't considered overpowered by the community and all these changes will do is encourage more Iowa players which already crowding the tier 7 matchmaking.

The counters for the amagi are there already HE spam and because of it's weak armour other Battleships hitting it's side with good penetration shells. E.g Iowa/Bismarck/tirpitz/Alabama

The suggestion for balance fixes for the iowa are commonly stated on reddit.

Iowa accuracy reduction and a damage reduction so the shells are closer to the Amagi shell damage region shuch as 13800 or 14000(those numbers are just ball park figures)

For the amagi I would consider looking into the players who do well in the amagi as I wouldn't say it's just because it's a good ship. It's hard to play well and I strongly disagree with punishing players who do well in a ship that is difficult to do well in.