The champs are always the team to beat. And look at the collective experience. On top of that, they've got nagging injuries all throughout their lineup: Chalmers, Battier, Wade, in particular are not at 100%.
It's early days and they're still the 2 seed regardless of anything. There'll be article after article about whether they need to trade, the fact that they have no interior D - as exposed by the Knicks last night - and so on, but the fact remains that Miami are still a super team, and they still have the best player on the planet.
Only injuries will stop them, but that's standard for any and all elite teams in both conferences. They're absolutely the team to beat until their season is over.