The problem with being the most high-profile player at a certain club is that – as Rangers have proved over the last week – there’s always a risk you will become a lightning rod for criticism. See Marcus Rashford at Manchester United, frequently singled out even when he is performing head and shoulders above some of his team-mates. Remarkably, Cristiano Ronaldo was not immune to the odd boo when firing in an avalanche of goals at Real Madrid. And with the sting of that 3-0 Old Firm derby defeat to Celtic still throbbing away amongst the Rangers faithful, a man who struggled to cope with the ir…