Strange one is Berchiche. He was a real stand out at U18 level for us, really solid defender. We let him go and I was sure we hadn't heard the last of him. I kept a eye on what he was up to and, to be honest, for three or four years the answer was - not much. He was playing lower league or making sporadic appearances for Sociedad. All of a sudden, with Berchiche in his late twenties, he seems to have finally started to fulfil his potential. Good luck to him.
Look at Vardy too. He looks a real top level striker and didn't look out of his depth in England Vs Germany - he's 29 and was playing for Halifax Town a few years ago!