Simon, you got the idea, just past the blame. No way a Man U player could be at fault!
Your right, left side of the box is not where a striker should be providing defensive cover. Normally that's an area the left back, or left midfielder should be. Or, depending how the manager is organizing the defense of a 1 nill lead, anyone assigned to man marking.
Think a little harder. Passing the blame is the easy way out. The whole team were to blame, Rooney, Gerrard, Robinson, the entire back 4 including Rio, etc, etc, etc.