I take your point and you are right about the general underperformance but he hasn't merely underperformed. He's been pretty wretched. But as you say, not helped by the poor performances of our defence, our tactics and the unwillingness of some players to press.
Like Mangala though, he looks like a player who just hasn't the skill set needed for the league no matter how good they may be in other leagues.
It's just that we have limited options in the out field, although god knows I'd rather see anyone but Kolorov at CB or LB. Or Fernando.
At this point I would prefer to see Willy between the sticks today.