I must have watched a different game today, I thought he was fairly poor. Not the worst performance I've seen but nowhere near man of the match, Mirallas Coleman, Barry, and Barkley all had better games.
He looked okay going forward but was atrocious at defending, I remember several points in the game where we were on defense, and he was marking open space with no one around him and no chance of being goalside of a player if the pass did come his way. He was clearly at fault for the first goal and it seemed like in the second half Swansea were picking on him by attacking down that flank. Especially when he's playing in front of coleman he needs to improve the defensive side of his game.
I think it's possible that he will come good but he needs to drastically increase his fitness, improve his discipline, and focus on developing the defensive aspects of his game. In a Martinez team an attacking player who cannot defend is a huge liability unless he's in one of the top two positions (which is why our team has only looked good with Osman in it when he's played in the hole)