Liverpool were once again indebted to the genius of Alexis Mac Allister to pick up another Premier League win tonight. Mac Allister has been imperious of late, making the difference in virtually every game he’s playing for Liverpool. That culminated with a quite brilliant performance against his old club, Brighton, on Sunday. The Argentine put the match-winning ball on a plate for Mohamed Salah with a truly ‘world class’ pass. And today, he was at it again. Despite playing in a slightly deeper role against Sheffield United, Mac Allister still affected the score line. Latching onto a loose ball…