Alexander Isak is yet to hit top form for Newcastle United this season. The Sweden international was outrageously good last season. He scored 25 goals in all competitions, as Newcastle’s most expensive signing ever enjoyed the best season of his career. Even more was expected from Alexander Isak this season. Emil Krafth backed Isak to score 30 goals, but the 25-year-old is well off the pace required to hit that tally. So far, Isak has scored just once for Newcastle United. That came in the 2-1 victory over Tottenham Hotspur, as he netted the winner. He struggled last week, with Isak missing so…