Note that quantum modelling those effects go as O(a^N). If you want to hand-wave away exponential computational cost, then I cry foul: the details matter, and I posit that you cannot build a computer that is more powerful than the universe itself.
What I'm suggesting is that the calculation never needs to be done, which means the complexity of it does not matter. Whether it's O(1) or O(a^N) they're both far smaller than the infinite number of potential states.
Well, that's your preference then. But personally I want to see the Mets play the Yankees because it's profoundly unsatisfying to believe that all possible outcomes are computable and therefore on an equal basis. I daresay that idea is so bad that if you took it seriously, it would die out with your genes/memes. (Not that that matters since you could travel to and impregnate every woman on Earth).
So, subjectively, it'd still feel as if you'd gone to the game without knowing what was going to happen and then exactly one outcome (and not all outcomes) happened. But from a more objective perspective, all outcomes are indeed on an even footing.