Grella gets paid very little so he shouldn't be shouldering most of the blame for struggling against teams who bunker. In terms of those front 4, BWP and Sacha deserve most of the blame for struggling against those teams. They are supposed to be our best players and are paid as such, they have to figure it out more often.
But then again, even Barcelona struggles against teams who bunker. It's the only reason a team like Celtic could beat them in the Champions league a couple years back.
Are you somehow suggesting that Tony Watt is never gonna become Scottish Messi?