I've finished playing "biggus dickus". It is a very good map, but it is too easy.
You know: I almost always say "It is too easy", but I think you want the truth and not a lie.
You can assemble a strong army with the first waves of attacks, provided you can defeat, capture and convert these opponents. And you CAN defeat them easily. The blue and green keepers are therefore not a serious problem.
I think it's really just because the start is too easy, because the rest WOULDN'T be so easy if you weren't so strong.
AND: The yellow keeper could also put up a bit more of a fight.