Its basic defending for any defender. Lindelöf didnt mark his man he is at fault for that. AWB had his man and let him just walk off in the box thats criminal. Im sorry but its unaaceptable to do that. Maguire and Lindelof positioning was off in that case AWB should have covered.
I would happily sell everyone in the back 5 including the keeper
Yeah.
For defenders the key is to assume the worst case scenario and act accordingly.
The CAF laughs at David Luiz because he often sacrifices his position and gets done by through balls. However, he does that because he assumes Arsenal will win the ball and he wants to be on the front foot for the turnover. It's the wrong mentality for a defender.
For an attacker you want them to assume everything will go well. You want them to be on the run if the pass makes it, or coming near post if the cross beats the man. You don't want them stood still assuming the ball wouldn't come.
Defenders have to do the opposite: they have to assume everything will go wrong. We won't stop the cross, the guy behind me will beat his marker, I have to deal with this or else they will score.
Our defenders too often don't behave like that. They don't act like they realise the danger around them and that they have got to do something about it. Lindelof is the worst offender for this too.