NBA finals - home teams are expected to win, yet phx suns series win probability increased after winning g1 and g2 at home. how to explain? nba finals is a best of 7 series (first to win 4 games). in the nba, home court is decently advantageous, to the point where the home team is generally expected to win.
this past week saw the phx suns win g1 and g2 at home. not an unexpected result, but the probability of them winning the entire series also increased substantially (60% prior to g1 to 88% post g2).
my non-qual understanding is that they have banked two wins. so regardless of whether or not the predictive models expect them to win home games 1 and 2, they have proven it. by proving it, they have changed the parameters of the predictive modeling - no longer is it a 7 game series, first to 4 wins, but now it is a 5 game series, where phx suns have to win two out of 5, and the bucks have to win 4 out of 5.
so is the 60% actually comparable to 88% since they're talking about different things?
let me know if i can better explain the situation.
the question is: if the suns are expected to win a 7 game series (60% win probability), why does winning games 1 and 2 at home increase their win probability to 88%?
if they are expected to win games 1 and 2 (let's say 100% of the time), why would their series win probability increase when the events are occurring as expected?

While winning at home is very likely, there was still a possibility of losing those games at home. The original probability included that possibility, now we have seen the first two games and there's no longer any uncertainty about their result.
Depending on how the probability is calculated, it may also reflect an updated belief on how the teams stack up relative to each other (obviously a lot was known from the rest of the season already on that, but this is still also extra information one can take into account).
