I think you are getting different games and try to mixing them up which isn't helping clarifying the issue:
in the forum discussion you listed above, you were saying minutes are being reduced for exhausted players, which is true.
in the game where you think you lost a big lead in the 4th quarter, your SF was explicitly described as exhausted in the play by play and we know the exhaustion effect kicked in - and during the three minutes where your SF was exhausted but remained on the court, your team went from leading by 7 points to trailing by 1 points, pretty much showing the effect of exhaustion
on the other hand the game in question does not have any player being described as "exhausted", nor was any of his starter getting 40+ minutes. If there is tiredness, it should be pretty close to his opponent's tiredness, and the scoring margin were definitely a lot more surprising then the games in your case