In what proved to be an incredibly frustrating evening for Liverpool against Manchester United yesterday, one player really struggled in particular. Jurgen Klopp has always been willing to rotate his teams in the FA Cup over the years, sometimes he’s even been criticised for doing so. But it felt different this season, Liverpool definitely sent out a team to win at Old Trafford, and for long periods it looked like they would. However, once the game became stretched it seemed to suit Man United’s attack who were pretty ruthless in extra-time. That being said, there was no such impetus provided …