As redemption arcs go, this is a comeback even the most saccharine Hollywood script would struggle to get away with. From rock bottom to back again, Manchester United’s 4-2 win over Sheffield United – on the same night that Jurgen Klopp’s Premier League title hopes suffered a fatal blow – proved that Old Trafford is home to our very own ‘mentality monster’. In the build-up to Wednesday’s clash, Blades boss Chris Wilder could hardly have been more glowing in his praise for a man who actually started his career in the red-and-white stripes. And, fittingly for a man born in the so-called Steel Ci…