It's not so much that Lebron lost them the game. But it's just hilariously funny that he seems to be completely incapable of putting his team on his shoulders in the 4th like Durant just did (btw, in Durant's first ever Finals game).
The game was basically even going into the 4th. One superstar took on the challenge and succeeded, the other one didn't - the one who is the supposed league MVP.
No one is calling Wade the league MVP right now. But yes, the reason you guys lost the game is bigger than Lebron's forgettable 4th quarter. It's just it doesn't bode well for you that Lebron hasn't got the 4th quarter monkey off his back. You have to be capable of winning close games, not just front-running in blow outs.