By Jamie Spencer Manchester United legend Wayne Rooney has suggested the club’s current struggles come down to a lack of leadership within the squad always keeping standards high. Rooney was a teenager when he joined United in the summer of 2004 but was immediately able to look up to the likes of Gary Neville, Paul Scholes, Ryan Giggs and Roy Keane as serial winners, copying their mentality and the examples they set. As that generation aged and was gradually phased out, Rooney found himself part of a new leadership group alongside the likes of Darren Fletcher, Wes Brown, John O’Shea and Michae…