Somebody might have already mentioned this, but you can't balance specialists who do different things, its like comparing oranges with apples. If everything were to be perfectly balanced you would only be able to have 2 (1 positive and 1 negating) specialists in the whole game. The only reason this game is interesting is because the specialists are not balanced, but they aren't TOO unbalanced either. I know many people think kings are OP and etc, but imo there are other specialists that are probably better in more situations (they are just underrated). If you've never had 4 tycoons or 4 generals you should really consider experiencing what it's like before you say 4 kings is OP. I have had all of the above, and I can say that 4 tycoons is practically always better than 4 kings (you just need to acquire the skill of managing electricity properly), and 4 generals is arguably better than 4 kings in domination and about equal to 4 kings in mining (and even more so with a diplomat). Seriously. You try it.
So my point is that, when created, want people to be disagreeing about which specialist has the best value, and at this rate I think the only reason it hasn't had this effect is because nobody ever tries out any of the other global stacks anymore (only king stacks). If you have I'm sure you'll agree its probably only slightly worse or arguably better than a king stack of the same size.
oh and its worked for me anyway because I think tycoon is the specialist with the best value. (Because you get + over 50% as opposed to +33% - 20 shield (thats just one of the reasons))
Kings aren't OP
"Imagination is more important than knowledge"
----Albert Einstein