Sigh... every time someone abuses statistics, God kills a kitten.
For your example, it does not mean that your AA was 3.4 times as effective. Your AA could be just as effective as in the last game, but the AI just threw 3.4 times as many bombers your way. You'll need proper counterfactual statistical methods to be able to disentangle the effects.
But it still helps to know that, as you will know that the enemy has built quite many planes so it should be weaker in other areas. Or, if you killed a lot of tanks or a lot of infantry, you know what your opponent has been producing. Also, that could probably mean that he is low on manpower.