Man, that's really easy to argue after the series is played! I don't think anyone in the country actually thought the Warriors were a better team than the Mavs before that series.
I know someone who seriously picked the Warriors to win that series. I thought it would be a close series and wasn't shocked that the Warriors won. They were better than their record showed due to the trade getting Stack Jack, Al Harrington, and the other guy.
When I said "anyone in the country" I was exaggerating. I doubt seriously your friend would have been surprised if the Mavs, with home court advantage, had won. It was a shock, and that's why it was fun.