The Cavs were down 2-0 to two different teams in the playoffs last season, the Pistons and the Spurs. They came back to beat the Pistons 4 - 2, but they got swept by the Spurs. The question is, is this current Celtics team more like those Pistons or more like those Spurs.
My opinion: The Pistons of the last two years have not been "real" contenders. They were elite a few years ago due to catching lightening in a bottle with 5 very good players that meshed perfectly as a team with a hall-of-fame coach. Replacing Larry Brown with Flip Saunders and losing the "Big Ben" version of Ben Wallace took them from "elite" to just "consistently good". Consistently good is enough to get to the ECF in a very weak time period, but I don't think they'd have sniffed the WCF. If they were in the West, IMO, they would have not only been a level below the Spurs, they'd have also been below the Mavs and Suns of the last couple of years and battling it out with teams like the Jazz.
The Pistons were extremely vulnerable to transcendent talents on the opposition, because they don't have any of their own and their transcendent team-ness left with Brown and Big Ben. This is why they have been given fits by LeBron and Wade for the past few years, and it was not surprising to me when they lost.
For those of us that are superstitious I'll avoid making any kind of future predictions of greatness or wins, but I will say this: All season I have thought this Celtics team was much more similar to the Spurs than the Pistons. The team roles, the defensive mindset, the transcendent talents, just across the board this team has always reminded me of that San Antonio unit. The Cavs could beat the Pistons by just making it a defensive battle where nobody can score easily, then relying on LeBron to outgun the "good" players on the Pistons. But I don't see that strategy working for four games against this Celtics team, who has players that on any given night can be the best player on the court even if that court includes LeBron.