Some of this could be the result of compartmentalized development combined with poor communications. I could easily see them starting off with team A making the combat engine and team B working on the specific unit stats. Team A makes one screw up in the engine where shield values get inverted, but it doesn't cause any immediately obvious problem and isn't immediately diagnosed. While B is creating units and trying to make them work against each other with the engine... if the inversion happened early on in development, but after a lot of units were getting laid out, it could have been missed a while. Team B would be busy trying to make the units work inside the engine, and might have been told the engine is fine or locked and just had to work their best with it to compensate. Hence what we see... almost balanced in some fields, but when considered as a whole the something is far off. I can also easily understand how someone working on a couple units at a time could easily miss something like this. It's a problem that doesn't even seem like one unless you step back and look at the big picture.

But anyway, until the underlying engine is repaired, nothing "Team B" could have done would have gotten everything to work together right. And I will grant you, there is a chance that the fact the game is as playable as it is right now might be thanks to monumental 11th hour effort on "Team B"s part. Still, that's duct tape holding things together in a way while actual structural repair needs to be done. It's like a fresh coat of paint being used to hide cracks from earthquake damage... might look fine, even pretty, but it still needs repair.