Negative. He did live up to the potential. Last 6months season 2004/2005 Capello started playing him as a regular starter and he did make huge difference playing alongside Emerson.
He didn't have a chance under the Vieira-Emerson though in Capello's 2nd year. Many top English clubs were interested in him but obviously non of them offered like Fenerbahce. He was earning Millions there.
He had a fantastic WC06 and was Ghana's best man with Essien. He's no Lampard or Deco but he can still perform at a high level.