Since he's a favourite suggestion for an expensive transfer, on Eriksen's goal last night to win it for Spurs he did something some posters often criticize Chris Smalling for doing. Number 37 Skriniar moves out to the left to mark Son when Asamoah has pushed up from left back and Sissoko has been passed into some of the space that Asamoah has left behind. So Skriniar is covering Asamoah at left back.
Sissoko drives forward with the ball and actually Skriniar doesnt even commit to making a challenge, he allows Sissoko to run the ball inside him and then Sissoko who is now inside the box plays the ball to Alli also inside the box and he finds the free run from Erisken again inside the box to finish off the chance for the winning goal.
Normally when Smalling pulls wide to cover a fullback who has an attacking player taking up the position behind them he'll at least try to block the cross, or confront the player with the ball and try to make a tackle. He won't always win the ball. And sometimes the ball is then played into the middle where Smalling has moved from and posters on here will blame Smalling saying its his central position, his responsibility.
But its good defending for a CB to cover their fullback, it just requires teamwork for other players to understand thats whats going on and they need to adjust their positions. Skriniar doesn't confront Sissoko, he does let him get through the middle too easily but I'm sure he'll say that he had confidence in his teammates, De Vrij his CB partner and D'Ambrosio from RB to adjust their positions to cover the area he left behind to deal with Son and Sissoko out wide. But on this occasion Inter's defense has got it wrong.
Because Asamoah was out of position in the first place, it was 3 defenders where there should be 4. Because Skriniar let Sissoko inside him centrally too easily, De Vrij decides to come across and try to confront him. Doing that pressures Sissoko to try and pass and he finds Alli. So now the only player in the central area of Inter's box is the right back D'Ambrosio. Unfortunately for him while he's close to Alli, theres a pass on to his left to Erisken joining play and actually another pass further to Davies also in space. Either one of those players could finish the move. So D'Ambrosio has been given 2-3 players to deal with which is not really his fault and he cant stop the shot coming in. Inter's defense as a whole got that one wrong starting with Asamoah committing and getting nowhere near the ball 10 yards into his own half. But then Skriniar does a poor job with his covering. He is covering his fullback and thats the right call, but he does a poor job when he allows Sissoko to do exactly what he wants to do and run the ball into the box without any pressure from Skriniar. De Vrij does something but its leaving his right back a lot to do and then Spurs score because he couldnt deal with all 2-3 players.
One mistake, and particularly one mistake where he's come out to cover for another player, doesnt mean Skriniar isn't a great CB. He wasnt in that piece of defending, but that doesnt mean he isnt for most of the rest of the match. Likewise when Smalling covers for Young/Valencia and then he either doesnt block a cross, or a player beats him, or the ball comes across and someone has an easy chance because Smalling isnt in the middle... Thats just something thats going to happen sometimes and it doesnt mean Smalling isnt a very very good CB. It means that as an entire defense the organization, planning and reacting to the situation wasn't good enough. And usually Smalling does better than Skriniar did this time. But at least its a good example that the grass isnt always greener just because a CB isnt Chris Smalling. Even the most talked about, most hyped up CBs do the very same thing and sometimes do it worse like here.