I don't believe in any such complex algorithms, because of two reasons:
a) The "laziness" of the Firaxis team ("make the largest amount of money with the least amount of effort")
b) Ockham's Razor: "Among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. Other, more complicated solutions may ultimately prove to provide better predictions, but—in the absence of differences in predictive ability—the fewer assumptions that are made, the better."
So as long as there is no significant evidence that the current theory is wrong, there is no need to replace it by a more complex theory (involving hardy, normal and soft types of units). In order to prove that theory, you would have to somehow create 3 stacks consisting of only units of one "type", run 1000 combats with each stack and show that the outcome is indeed significantly different, I guess. (Or ask the NSA to steal the source code for us...)
a) The "laziness" of the Firaxis team ("make the largest amount of money with the least amount of effort")
b) Ockham's Razor: "Among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. Other, more complicated solutions may ultimately prove to provide better predictions, but—in the absence of differences in predictive ability—the fewer assumptions that are made, the better."
So as long as there is no significant evidence that the current theory is wrong, there is no need to replace it by a more complex theory (involving hardy, normal and soft types of units). In order to prove that theory, you would have to somehow create 3 stacks consisting of only units of one "type", run 1000 combats with each stack and show that the outcome is indeed significantly different, I guess. (Or ask the NSA to steal the source code for us...)