Why assume that someone's best game is always identical? Why assume the opponent's best game is always identical? One of the defining characteristics of the all-time greats is the consistency at which they performed a high level. There is a reason for that. Plenty. In that scenario under those exact circumstances, the stronger unit is always stronger. Change the circumstances and you could easily change the winner, even with 0 RNG input. This is quite similar to me asking you how it's realistic that a corn always yields 6 or that cow is consistently worth the same amount...in fact that's even MORE of a reach than deterministic combat at civ's scale. Civ was designed to be unrealistically deterministic in virtually every non combat regard except for huts and in the case of BTS, events. I ask why combat must be the exception.