Quote from nullheadnot really, I can do a good job on castle without that, just saying, and now I'm above that. (for now) but seriously, if you just know how, you can pull off just about anything.
and just because you havn't reviewed your strats doesn't mean that you're not good, just the opposite actually. You should never fight the war you just fought.
On castle, the map is so small if you control the center, you basically have disabled their second row of gold if you have your units at the center. You require a powerful start to take over the center and the two most powerful starts are rage swords and archer + sword, archer + sword comes out faster and will be ready to fight well before the one minute mark, and with the shortness of castle, they will quickly gain the economic boost and land claim unless facing another archer + sword. They can then out-sword the other person or get a castle archer which will dominate a third of the map early game.
Castle is ALL offense. Thus, Archer + Sword.
I'm in the 1800s, but I know what I talk about.