Manchester United legend Ruud van Nistelrooy has turned down a return to former club Heerenven while refusing to rule out a spell as a manager in the Premier League. While it’s fair to say not too many of Sir Alex Ferguson’s former charges have enjoyed considerable success in the dugout – see Steve Bruce, Mark Hughes and (briefly) Gary Neville – the early promise displayed by the legendary Manchester United duo Michael Carrick and Ruud van Nistelrooy suggests they could be an exception to that rule. Carrick guided Middlesbrough to the Championship play-offs in his debut season and the semi-fin…