Normally I don't try to play armchair psychologist, but I just don't see the Heat from 1-15 busting their hump at this point.
Lebron, Bosh and Wade aren't stupid.
They know that the odds of winning this series from being down 3-1 is pretty close to zero. They also know that they're in the East and barring a catastrophe they have an annual cakewalk to the ECF, and that right now there are no credible contenders to the Finals in the East given that the Pacers are a wreck, the Nets are are nowhere near being contenders, and the Bulls being a non-threat due to lack of scoring.
They're tired, they're banged up, they know they're going into the off season with player options and the possibility to sign with either another team, or re-sign with the Heat to make cap space to get more help (and a more credible run in 2015). Why on earth would they put everything on the line for a near lost cause when they weren't even putting everything on the line in a must win game 4?
Wade can just roll out another hidden injury excuse. Bosh can just say that he was playing his role. Lebron still has nice box stuffing stats.
Between the Spurs being favorites through displayed dominance through the play offs and the complete MIA play of Chalmers and Cole, they have a perfect set of scapegoats to let them off the hook.
And let's not forget this is their 4th finals run and they already have 2 championships. They're not going to have the same desperation as some bunch of young guys chasing their first chip who'll risk life and limb on a lost cause, especially since none of them (except Battier) are considering retirement any time soon.
I think it's quite possible that they'll put in a decent effort initially and see how it goes, but if it starts going bad they'll go through the motions, lose the game and congratulate the Spurs for being an amazing team. Then regroup for next season.
Could the Heat win? Sure. However, I think the Spurs take game 5.
J.R. Smith: "They were pretty much scoring at will. Especially my guy. I don't know what the hell I was doing on defense."
Raymond Felton : "The play was give the ball to Melo."