Xavi played well for the first 2-3 months and then fell by the wayside. He just had the one good game vs Milan in the second half. I'm one of the biggest Xavi fanboys on this forum but I can readily admit he has been way below par this season.
He has been reluctant to release through passes for whatever reason and his defensive contributions have dropped dramatically. Even aesthetically, his game has dropped big time.
I don't think he's past it completely but he should obviously be played less. He must also convince Messi to move his ass. Even last season, Messi's movement was outstanding, he was one of the most intelligent forwards in the world in addition to being the most skillful player in the world