I agree there are some unrealistic results from the game engine but I think you're referring to unrealistic things fed into the engine? Not sure what you're talking about there.
Figuring out what led to victory when multiple factors could be responsible is a matter of trial and error. Just play the same defence with players of worse/better stamina and see if you win, etc. Vary the degree of stimulus and see how much response varies. Works for figuring out most anything.