Sky Sports pundits Jamie Redknapp and Sol Campbell pointed out a key mismatch in Arsenal's defeat to Tottenham Hotspur.
Spurs scored the winner when Toby Alderweireld outjumped Kieran Tierney headed home from a corner with 10 minutes to go.
It completed a comeback victory after Son had equalised shortly after Alexandre Lacazette's fine long-range strike.
Yet Redknapp questioned Arsenal's defensive set-up for the winning goal, arguing that someone else should have been marking the Spurs centre-back.
He said: "It was a good bit of play from Tottenham initially but I'm not mad on the set-up.
"They go three zonal - Xhaka, Luiz and Mustafi are almost marking to attack the ball and Tierney is with Alderweireld
"Alderweireld is one of the best at this, he gets up so well and wants to win it.
"He's just too strong for Tierney with too much knowhow and he's a centre-back.
"I think that's sometimes the problem, it almost felt like there's certain players who need to be picked up in that situation.
"Sol Campbell would take the initiative there, he'd say 'I don't want that, that set-up doesn't look right'.
"I didn't like the set-up from the start.
"It's a brilliant header, he's one of the best in the business at that and I think that makes a difference."
He added: "When you're in that position, you know if someone's got the jump on you and you don't feel comfortable about marking somebody.
"Tierney would have felt that with Alderweireld, he was too powerful for him."
Campbell agreed, labelling it a marking mismatch.
He said: "It's a mismatch of body strength, experience and things like that.
"You could have switched that over and had David Luiz marking him instead.
"I'd have players marking each other of a similar kind of size and experience.
"In those key moments, you need that experience to make the difference.
"It was a mismatch."
