I am beginning to believe that the devs recycle old code. The reason I think this is that something will get fixed then a few releases later that same bug shows back up again but they are able to correct it quickly the second time, and the third time, etc... until they finally get that item out of all the code pieces that are in development. Insert many recurring bugs that come and go with new releases and it makes you wonder.
So you team that worked well with the current AI might find that against the updated, or possibly outdated, AI it plays slightly differently. Then the next update comes and your team works well again because it is back to AI v2379.8 instead of AI v2378.6.
I'm speculating of course, but I can't imagine how some of the bugs keep coming and going if they aren't reusing at least some pieces of old code in the development. And as complex as this game is I can't imagine not reusing code to keep the development pace moving.