NHL is obviously a lot different though..when a lower seed beats a high seed in the NHL, it's not surprising at all..a lot of people expect San Jose to lose in the 1st round this year for instance..
As for Miami, they're probably the worst le team of that time, but I wouldn't call them lucky..it's not like they had a bunch of buzzer beaters or had the fortune of injuries to the opposing team..Wade was the best player in the NBA that year, they had a bunch of hungry veterans and a well-built team..I guess you could say that they were lucky that they got the Mavs in the Finals, but we see more luck than that on a yearly basis in the playoffs(Lakers easy road last year due to injuries, Spurs avoiding Dallas in 2007, etc)..