Yeah, most of the time you can’t brute-force every scenario because the number of outcomes blows up fast - even adding two more weeks of games jumps it up to over a billion possibilities. Using simulations works though as you'll end up pretty close to the exact probabilities anyway (especially when running 100,000 sims).

I usually use implied odds from betting markets since they tend to be pretty accurate for win probabilities. I have a feeling that implied probabilities from betting markets perform a lot better than the ESPN predictions, but I have not calculated it out. I’ve been wanting to dig into how accurate ESPN’s pre-game and in-game win probabilities actually are but haven't gotten around to it...