The numbers look fairly even to me. I don’t think there is much of a question that the Axis start out with the ability to do a ton of damage in rd 1 and can realy put a dent into the Allies. Germany can smash multiple Russian territories with Russia being limited in countering and Japan can really go crazy. So I think that the Axis need to severly outnumber them in terms of IPC and do so for several turns. Remember the supply lines for Japan (to Moscow) have been extended. I don’t think an Allied deficit of 10-15 ipc per turn is that bad (maybe Axis 120, Allies 105), however, if you get into the 20-30 range for multiple turns then it is bad news. Anything under 10 can be potentially be written off by dice (ie when one lone inf hits on def, or maybe 2 inf hit out of 3-4, bom shot down due to aa, etc).
So I still think that for the most part the longer the game goes the better it is for the Allies.
I think one of the biggest factors is how quickly can the Allies kill the Italian fleet. If you get it by round 3 or 4 you are in good shape, anything after that and you might be pressing your luck.