You must not have been very good at algebra - if x >>> y and z = c, it doesn't necessarily mean x > c. In other words, San Antonio easily dispatching Memphis isn't grounds for dismissing the two more evenly matched eastern conference teams as a threat. My take is this: Indiana has the perfect collection of players to expose Miami's one, and potentially fatal flaw, which is the lack of a pure center. The Indiana-Miami series is actually very reminicient of the USA-Spain gold medal game a year ago - one team has a noticeable talent advantage, but the inferior team is able to combat that by continually hammering away at the favorites achilles heel. In the gold medal game, it was the Gasol brothers (more prominantly, Pau) carving U.S.A.'s interior defense like a Thanksgiving turkey, while in the Indiana-Miami series, Roy Hibbert's opperating with the ease of Ater Majok shooting over a chair, and David West's raw strength has discouraged Chris Bosh from mixing it up inside. Miami's identity (their unique ability to play small, present hellish floor spacing difficulties to the opposition, and yet lose nothing at the other end) has been thoroughly squashed by an Indiana team refusing to relinquish their own. Indiana also possesses the most well-orchestrated defense in the league, one of the brightest young basketball minds in the game, and a blossoming star in Paul George. Truthfully, I'm not at all surprised at the dogfight this series has been. While LeBron's numbers in this series have been largely on par with what he normally submits, Roy Hibbert, a game-changing defensive talent, has managed to accomplish what no other player in the league to my knowledge has been able to do, which is negate LeBron's ability to finish at the rim. I think this, in addition to the athleticism and length Indiana offers at other positions, has sapped some of LeBron's dynamic defensive ability and allowed easier looks for Paul George. It's not easy to play 45 minutes at an elite level at both ends of the court, which is what LeBron's been asked to do in this series. The "LeBron can guard every position on the floor" narrative has been rendered a mis-conception in this series - LeBron can guard some centers, he can't guard centers like Roy Hibbert.
So, as 3rdbass said, it is about match-ups. San Antonio is just as good as Indiana, and probably better, but after getting the ever-living kicked out of them for seven games, I think an aging Spurs team will be a welcome sight for the Heat do they manage to survive.