Quote Originally Posted by Blah99200 View Post
Against a 5k defense, the mixed mech is more efficient mainly because pults will get 2 rounds of fire on the defending archers, as opposed to just the one round ballista gets, resulting in your much higher damage output from the mixed mech. With a higher attack hero, build times also become much less of a factor, and as your analysis of resource cost showed, the mixed mech will yield a better damage per unit cost.

I think the only times a bally bomb is arguably better is when there is a shortage of Level 10 barracks to produce the pults, as well as a lower level/attack queuing hero. Both of these are usually present during the early server, and even later for those that don't coin, or are not able to focus as much time on their game.
I know why it is more effective, that wasn't the question I was asking. I was referring to the benefits of food costs/march times vs the initial resource cost of the builds.