Au contraire. I can root for Boston to win if they play just as effectively on defense.
Then we don’t look stupid.
I understand this line of reasoning, following it myself. Unless the team that beat us in the playoffs is an arch enemy, or just complete jack wads, I usually root for them to go all the way so as to make it look like: “Well hell, OF COURSE the Sox lost - nobody was able to take down those guys....”