I think it is simply that the blue team is able to build faster due to a better tree distribution. Whoever is able to get their quarters and armory first should be able to take the game so long as they put forth a lot of effort. At the blue I've been able to not only out build opponents who have more starting peasants, but also fight evenly with berserkers using only axemen. It appears that the only cause for weakness is tree distribution, because once the opening (resource access) is blocked off the person has very little chance of recovering.
Oh, in regards to being weaker when playing yellow, people guarding the yellow entrance are higher up than you are. That means that your people have to run up close to be able to throw up. It's the same principle as being up in a tower, when throwing down you have a longer reach and are thus stronger.
I doubt this is very high on the list of priorities in the software production. Just think of it as a handicap. When I was playing you I had two more peasants than you did, if you were claiming your actual peasant count. However, when you played blue you managed to finish building things faster. It enabled you to build at the same rate as a better equipped player, a good handicap if you want a challenge against a weaker player. You forgot that I still beat you once or twice when playing yellow...
