The inner logic isn't quite comprehensible. If the US is firing from sept. on, why wait until dec.? 2 things happened in dec. 41: Pearl Harbour and the defeat at the gates of Moscow.
But I fear we will never be quite sure about what and why that happens, this thread is discussing the question, if diplomatic action could influence major or minor nations the way it happens in game, and how this is influencing balancing.
It wouldn't be so badly, if there wasn`t this huge luck factor. Bill and Hubert both stated the use of diplo being a surprise compared to the predecessor; the reason is the hugely diminished effort, at far more opportunities. With far less income, more expensive units, research and diplo, the players weren't that keen on playing a gamble in Breakthrough SoE.