Shelvey flatters to deceive. He's actually a fantastic talent - he just doesn't seem have the drive or the motivation to be a top player - not that he's a shithouse or something - he just plays sloppily and without much effort at times.
He's only 21, two years younger than Henderson, and still only in his first ever real season in the PL. The coaches at Swansea need to sit down and really work with him, because he can actually be a top class player.
That said, that was his 5th goal in the league this season. Not too bad at all.