I noticed something in my ottomans game. You take a large prestige hit for uncontested cores. This does very little to a player (who almost always contests cores), but it can absolutely decimate an AI. Once you've taken a handful of cores off Austria or Hungary, their prestige rapidly sinks and it becomes much easier to defeat them. This penalty needs to be reduced by a lot. In my game, Austria has a penalty around -3.9 and has their prestige pegged at -100.