Of course he bottled it, he let the pressure get the better of him and took a shit penalty. Probably never taken a pen in such circumstances before (against former club, used to be adored by their fans, could send them down, just been hurled a load of abuse taking a corner 1 minute previously in the Strawberry corner), words from Anita and Cisse also probably put some doubt in his mind.
If Darlow went the wrong way nobody would've said a word, though. There's a difference between it being an imperfect strike (which it was, obviously) and a bottle job. Honestly, people don't half let their emotions produce some daft and pointless posts on here.