how i look at it is yes the zerg did happen to defeat the xel-naga but what, you said its been 10 years? Sometime has passed and remember the xel-naga also formed the protoss. So whats to say they dont take both races into themselves to defend themselves. They created both races and they have had many years able to figure out ways of fighting and how to defend ones self. But yes as you said, "For a unit 10x better than say the Zelot, the Zelot takes the longest to build for basic ground attack as it is... An online zerg will be at ur base with a 6 ling rush before you can even think about building a Xel-Naga unit." I think if they are creators and not true fighters wouldnt they know of some way to spawn their guys faster? I'm not saying blizzard is gonig to do this but i think if they did this would be how they balanced out the spawn time thinking for xel-naga. But then what about over powering? It all consist of upgrading a races units making them stronger over the years. But i see where your coming from