And the really huge one: there are no more mysterious AIP increase penalties for having too many fleets at one place. We'll deal with the exploits that you can potentially get up to later in terms of fleetballing too much, but the first solution we had was just plain irritating and not good. There is discussion about potential options here, if you want to get in on that.
When you think about it from the perspective of the AI the most logical conclusion would be:
If i am suddenly attacked by this unusually large mobile force, it means that the weak humans do not have many mobile reserves to defend with. If the human fleetball is not assaulting strategically critical location, I will;
...assault their most strategically important points with fleets specced for dealing with turrets/mines/forcefields.
... will make the attacks happen as far as I can from the human fleetball, so it will be late to defend.
... will try to keep the human Fleetball busy by engaging them with anything that can tank/slow units down/do engine damage/do paralysis/tractor units/
block wormholes. I will also send these units to the lines of communication between the human fleetball and my strategic assault points to slow their retreat.
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So I think there should be specific response to these fleetball events. I know this is sort of what the eyes did, but they were a local response, this would be a strategic response. And potentially a very dangerous one. We should of course explain it to the player. We can do it in many ways. When AI starts to act on a perceived fleetball, we should get a notification, when the AI is using its strategic reserves to contain large fleet movements. We should also make player see a change in the units that the AI is pushing at the player. Suddenly the AI does not care about defending the planet, instead just containing the fleetball for a moment. We get these mobility inhibiting/hard to kill units targeting the fleet-ball and staging at important points the Lines of communication.
Meanwhile we should also get announcements of multiple counter assaults to our rear. Accompanied by the old AI taunts that we suck at strategy and must therefore die.
I think this is in the spirit that we are fighting a stronger opponent, who only pays us attention when we get too cocky. But it wont actually stop the fleetball from doing its job that the player wants. But the player has to balance this risk versus reward. Do I risk my mobile fleet being stuck multiple lanes away when the AI is assaulting me? Or should I pick a good fleet or two for the job and keep the rest in reserve?
EDIT: From what I understand is that you want to utilise carrot instead of sticks. In my view this just isn't the place for it. The whole point is that we are fighting this much stronger but preoccupied force. This is the perfect place to let gameplay show that the AI does not mess about. If you present all your forces to the AI, it will bite hard. But the great thing is that it does not prohibit the practice of fleetballing. You just need to adjust your operations to take them into consideration.
But I think this is a positive shift since it changes the discussion from "how to prevent fleetballing" into "How do I deal with the AI response to my fleetballing?" or "is it too dangerous to fleetball right now?"