They don't blindly rush them. They trapped you in the ALL IN mission, you had to defend yourself constantly while the majority rushed you and Nydus Worms tried to spawn in your base.
And when they do invade, they use strategy dude, ALOT of strategy.
Just read about how Kerrigan did in the original Starcraft. Now that is an evil mastermind! XD
Brb, I gotta sleep. XD