<text>  It was staggering that Louis van Gaal did not turn to Radamel Falcao as Manchester United were trailing 2-1 against Arsenal in the FA Cup quarter-final. The poor lad must be thinking: What am I doing here? I know he is not the player United thought they were getting, but isnt it down to the manager to get the best out of him? Radamel Falcao second right was an unused substitute during Manchester Uniteds defeat to Arsenal . Michael Carrick right was brought on at half-time but Colombia forward Falcao was left unused . Goalscorers change games but instead they chased the match with Daley Blind and Michael Carrick, two sitting midfielders, on the pitch. Surely it would have been better to show greater intent by throwing on Falcao? United never threatened Arsenal once Danny Welbeck put them ahead and it is Arsene Wengers side who have progressed to the semi-final at Wembley. 