I don't think the guarantee was necessary for a couple reasons:
1. The Pacers(especially Artest) have already publicly stated how impressed they are with the Heat at home. The Pacers wouldn't of conceded game 6, but they know that they have the comfort level of going back home, and Miami is awful on the road. Why give them any motivation>
2. What is up with all these "home" guarantees..granted, the Heat's one carries more water, but Webber's was a friggin joke. "I guarantee we'll win game 6!"--ooooohhh, there's a shocker chris, afterall, you are playing at HOME. Did he guarantee a game 7?..nope, cause he doesn't have the balls to make real predictions. Guarantees should be saved for bigtime upsets, or tough road games, not Home games.