I was actually just waiting for you to commit against JR and then joined in some turns after that. My only way to win this was to participate in dogpile against JR but let others take the biggest beating from his units. Would not have gone after you before JR would have been dealt with.
So I guess a lot of things happened on the turn of the actual concession, but I still think JR4 would have easily won. That MFG advantage was ridiculous. But really, when things like this are happening, it's time to end the game: