Liverpool’s defensive frailties, Wayne Rooney’s nous in both boxes, an unwanted headache for Paul Clement and Manchester United’s unsung heroes The excellence of Romelu Lukaku and Nemanja Matic will attract most attention, but equally crucial was went on around them. Because José Mourinho omitted Ander Herrera – completely unnecessary against opposition likely to sit deep – he could pick an extra attacker, and whether that was Juan Mata, Henrikh Mkhitaryan or Marcus Rashford, the…