If Lebron breaks his leg , yea I think so. 
Why not? We are better now than we were when we met them in the playoffs and let's look at those results:
Game 1: Close game late, but Pierce was ejected and they pulled away.
Game 2: Another close loss in which were only down 5 to start the 4.
Game 3: Rondo gets injured. We ride the emotion and blow them out by 16.
Game 4: We lost in OT
Game 5: We had a lead in the 4th, but once again they pulled away.
The Heat do have their issues. They're struggling at the wrong time and today Anthony was removed from the starting lineup in favor of the newly acquired Turiaf.
During the playoffs we went with an 8 man rotation. The players that aren't on this year's team are JO, West, Baby, and Green. Those players were replaced by Steimsma, Bradley, Bass, and Pietrus.
JO vs SteimsmaJO is a better post defender, but against the Heat that post D is pretty much useless. That said, I would give the edge to Steimsma for the hustle and energy he brings to the table.
Green vs Pietrus
Green struggled adapting to his role, while Pietrus (hopefully back from injury) has become the long sought out Posey replacement. I would give the edge to Pietrus because of the way he adapted to the team despite Green's obvious superior talent. This doesn't mean I would take Pietrus over Green, just means that I think this year's Pietrus was better than the Green we saw in a Celtic uniform last year.
West vs BradleyWest played well during the Miami series, but I would also take the current Celtic here because of Bradley's superior D. West does play above average D, but Wade went off on him and Allen in a way that I don't think he can do on Bradley.
Davis vs BassNo contest. Davis was looking for a contract and continued to fire away jumpers that weren't falling. Bass and it's not close.