Can anyone explain why reccomended gear changes based on spec order?

So my spec order is feral, guardian, balance, resto. I started balance now and its trying to best in bags me from a 415 set piece to a lvl 395 piece? this would also remove my set bonus as well as the big ilvl upgrade, yet when I drag balance to the top of the list it doesn’t want to make these gear changes? wtf is this system? why does the order on the list even affect an individual specs gear setup?

It’s a priority system. You set what is most important to you (you can drag your setups). Most people do not want to change gems/enchants around every time they change specs. There is a toggle to force the newest tier you can try, and maybe it won’t change as much.

ekstren has the gist of it – say you have a good chest item, then put a gem/enchant in it for your top priority spec: balance. Now you want a feral set as a backup, but it’s not as important to you as balance – you only play it for fun from time to time. But you only have that one good chest item… you’re going to use it for feral too, but you won’t keep changing the gem/enchant every time you switch specs. You’ll leave it as whatever you picked for balance.

On the flip side, maybe you have a slightly lower quality chest item but with a more appropriate gem/enchant it would rank a little better for feral. The optimizer will figure out these tough choices for you.

So make sure you put your spec at the top of the list that you want to always have the most optimal gems/enchants, then add the others below it in descending order of importance to you.