His audio interview is up:
He says it's not a surprise as he can't hit two shots in a row at the moment, his serve completely lets him down too, it usually is one of his big weapons, so the scoreline is not that amazing in his opinion. He hasn't managed to settle his game down since the beginning of the season.
He has no explanation. Physically he's perfectly fine, he even jokes about it, he says things really couldn't be better in that regard and one has to see the positives.
His game and his confidence have just completely vanished. He's lost control of all his shots. It has already happened to him when he was younger, he'll have to learn the lessons from this terrible Australian tourney and back to work now so it doesn't happen to him anymore.
A transcription here, easier for the non native speakers: