Playing him at power-forward also makes life easier for Wade. Bosh has worked on improving his 3 point shot. LeBron’s 3 point shot isn’t bad – he shot 36.2% from 3 last year, compared to Kevin Durant’s 38.7%. LeBron and Bosh at the 4 and 5 can set up by the 3-point arc, and while neither is “Ray Allen”-accurate from 3, the opposing power forward and center can’t afford to cheat off of them too much because they can both hit the shot when left open.
If Wade drives to the basket in that situation, he either doesn’t have to worry about help coming from a PF/C, or if one of the bigs comes to help, Wade could always kick the ball to either an open Bosh or LeBron. Depending on how quickly the defense rotates, this leaves the defense vulnerable to breakdowns.

The concern about using him at PF for all 82 games due to wear and tear is valid, but Spoelstra has talked of managing all of the Big 3′s minutes better with the added depth.
Wade has a high-quality backup in Ray Allen that can play 20 minutes a game, so limiting Wade to 30 minutes a game isn’t complicated.
Bosh can be backed up by Udonis Haslem if the team needs more defense and rebound or Rashard Lewis if they need length and floor spacing.
LeBron can be spelled by Shane Battier or Mike Miller depending on whether the lineup needs more production on defense (Battier) or offense (Miller).

I realized the other day that most post players first have to jockey for position and then receive a well placed pass before they can do any damage. LeBron has the ability to dribble himself right into post position. The defense always stays a few feet back from LBJ (out of respect for his speed and lay-up prowess) leaving plenty of space for him to turn his back and bang into great post position. That dribble-to-post-position advantage is huge. From there he can just score or wait for the double team and hit a teammate on the hands for an open shot. I really hope he remembers the lessons of his NBA Finals performance by fully committing to his post game this year.

I think the overall issue isn’t when the Heat are on offense, but whether a good, bigger team can wear them down when the Heat are on defense. In a game or series LeBron can defend the 4 no problem. But, will he wear down defending the 4 and banging the boards for a full 82 game season, and then the playoffs?