I'm not sure what happened with Olly - i heard him interviewed by Graham and everything he said, Graham was undermining him - eg when he was talking about having to leave his pets to do the competition Graham said something like "well, you're going to be away for ages, did you not realise?" - making out that Olly wasn't a real Eurovision person or some such thing, I dunno, it was bitchy, is how it came across. I don't think he's had the full backing of the BBC stalwarts.
Maybe that made him nervous. Also when he performed there was something wrong with the sound mix. I don't know what it was but it wasn't right. I don't know what he could hear but if he heard what he did it would have definitely put him off. He's certainly performed it perfectly well before when he's sung live, on numerous occasions, so it's not like he can't do it.
Hopefully if he keeps his head down for a bit it will all blow over, but it's a shame.