That isn’t fair. He’s one of the best linesman in the world and has a medal for officiating in a World Cup Final to prove it.
He did precisely as he’s instructed to do. Correctly identified an offside. Delayed his flag until a potential goal scoring opportunity was complete and then raised his flag to advise the referee he thinks there was an offside. It’s not on him that the referee ignored that advice.
"He did precisely as he's instructed to do." Yes, instructed by Webb, maybe?
You just have to look at the clip circulating Twitter and other media. McCann is confronted by Fernandes and Rashford after he flagged for offside. After a brief discussion, Fernandes turns away with a smile on his face. This is before Attwell has spoken to McCann. McCann has already told Fernandes that the goal will stand.
Neither of us know what he said to Attwell, but my version is probably more credible than yours, which is to put the blame entirely on Attwell.
They are both equally culpable, as is VAR for not advising a screen review.
One of the cop outs is that it was a subjective decision. Really? No, not really.
This is an extract from Law 11. Rashford is offside probably on all four points. There is nothing subjective about this, he is offside as perfectly described in black and white.
Or there is this example, again from the Laws of the Game. This makes it quite clear that a player running towards the ball, preventing an opponent from being able to play the ball is offside.
This didn't boil down to a matter of opinion. It was offside according to the LOTG.