I don't think it has much to do with the fall of Antiocheia. In my campaign (Casse) it fell to the ptollies really quickly but the seleucids have lost no other territory except Mazaka but are still surrounding the lazy Hai, and beating back the not so lazy saba and pahlava (with the help of baktria) and still finding time to take india. The ptollies on the other hand have no sand wars with either Carthage or Saba while pontus and the west seleucids (Sardis and Ipsos) are keeping Egypt confined to Side, Tarsos (under Pontic control until a few years ago) and Antiocheia in Asia Minor.

Then in another campaign (Makedonia) I haven't got 15 years down the line and the seleucids have already taken Side and still have Antiocheia so I've seen more silver than gold deaths in my campaigns.