It is possible that he switched to Gold Arc 3 after the World Team event. He played amazing at World Team. Did not drop a game. I don't know anything. But, it is possible that he switched after the World Team event and is still not fully used to it, or it is not quite the right rubber for his backhand. And he dropped games in several matches in the Olympic trials, so he was not ripping through people the same way last weekend. And, in my opinion, the World Team was a bigger pressure situation because:
1) he knew that he had several chances to qualify.
And
2) He knew that no matter what he did, the ITTF rules determined that he was not going to be playing in the singles event in the Olympic Games.
We also know that Ma Long is using a DHS blade and might have reasons to use DHS rubber on forehand and backhand so that he uses DHS equipment exclusively. Could be contractual and/or national pride.
But there is no doubt that he got nervous and fell apart when he could not handle Koki.