While many still have doubts about the usefulness of the January window, Manchester United know from experience just how transformative one winter signing can be. Just one week after Ole Gunnar Solskjaer‘s side trudged off the Old Trafford pitch following a shock 2-0 home defeat to Burnley – one which left the Red Devils fifth and 30 points off top spot – Bruno Fernandes rode in on a white stallion and immediately turned around a flagging campaign. Four years on, Fernandes’ former Manchester United team-mate Nemanja Matic, even at the age of 35, has done something pretty similar at Lyon. Eyebr…