Swansea’s strong defence
Swansea’s deep, narrow, and compact defensive approach made this a difficult game for Chelsea to open space centrally in the final third and change the speed of the game to disorganise the defence.
From the front, Swansea would move to the sides to pressure, with Sanches moving both on the right and the left, Bony often in the middle, and Ayew wide or moving onto Chelsea’s nearest-to-the-ball central midfielder. Behind them, the three central midfielders would try to push up and get tight, but Chelsea could quickly and easily break this pressure with switches to the weak side, or playing through it on the strong side of the defence.
As Chelsea advanced into midfield, Ayew and Sanches would drop to pressure Chelsea’s central midfielders (both goal side and from behind, but always narrow). This left Swansea’s three central midfielders deep, also narrow, and close to the backline to protect them centrally. This left very little space for passes to be played into Willian, Pedro, or Morata, and when Chelsea could find the passing line to them they would always be met with instant pressure and surrounded by multiple opponents.
Since Swansea attempted to maintain control of the middle, the space Chelsea found was on the wings, where the wing-backs could advance and be found through diagonal passes from midfield, or occasionally through Chelsea working the ball from one side to the other in the final third. Of Swansea’s two full backs, Naughton was the more successful in defending the diagonals out to Alonso, where he was always out quickly and early to either head the initial pass away or be tight to Alonso when he received the ball to block the angle for crosses into the box. Zappacosta found much more space upon his first touch on the right, where Olsson would slowly move out to attempt to block the cross or prevent Zappacosta moving past him with his first touch or find a runner behind.
Although Chelsea often got into these crossing positions, Swansea still had numbers back early and their central defenders were quick to cover both the goal and runners inside the box, making clearances and ensuring there was at least contact on Chelsea’s attackers if they were unable to win the ball. Again, the space would typically be at the back post for Alonso, but in difficult positions to shoot.
Swansea unable to get out
Swansea’s defensive solidity came at a cost, however, where they were unable to hold the ball up at the front to get out of their own half and launch attacks inside Chelsea’s half. Long to Bony was unsuccessful since Chelsea’s backline were able to win the first ball or Kante could pickup any loose ball; and Bony was only able to win a couple of free kicks to provide chances to play the ball into the box. Ayew was solid at holding the ball and dropping between the lines to receive the ball, but his support was either limited or lost the ball—Sanches, for example, losing the ball consistently in the first half. Long to Bony would create situations for Swansea’s midfielders to move up to pressure the second ball in Chelsea’s half, but Chelsea were able to deal with this pressure by playing wide.
In the second half, Fer provided Swansea with a better outlet to play long to (both he and Ayew winning the first ball) as well as being able to keep the ball most of the time to find teammates—thus providing a platform to create attacks inside Chelsea’s half.
With the platform to hold the ball in Chelsea’s half, Swansea’s fullbacks could advance up the wings, the central midfielders could switch the ball side-to-side, and they would have numbers inside the box for crosses. They managed to work some positions to shoot from long, on the outside, and one good chances for Routledge to cross the ball into the box late on, but, for the most part, they were only able to create positions to shoot rather than quality chances to score—still better than having no shots in the first half.
Chelsea’s changes on the wings
Since Chelsea were finding space on the wings, Willian and Pedro began moving wide for the ball to use their dribbling or runs behind on the outside to get into better crossing situations (and more often) than the wing-backs. In particular, Willian was often beating defenders on the outside to play the ball into the box, as well playing ground passes into the box to create chances for both Pedro and Alonso—where Willian would move wide on the left (as Hazard has often done this season) and Alonso would join the box on the inside.
Chelsea’s set pieces
Some of Chelsea’s best opportunities to score came through set pieces, where they consistently won the ball in the air and their players inside the box were able to lose Swansea’s defenders to find space.
Swansea had good cover of Chelsea’s short corners early on in the game, where Naughton and Carroll would go out to match Chelsea 2v2. Mesa would be on the edge of the box to cover Kante if they played the ball to him, and pressure or block the usual direct pass to Pedro directly from the corner. When Mesa moved to pressure Kante, Ayew was there as cover to move up and pressure Pedro on the edge of the box.
Chelsea managed to find the breakthrough by taking a corner quickly and before Swansea could organise themselves defensively. Both Mesa and Ayew were still deep inside the box and too far away from Kante—leaving him space to carry the ball forward and shoot. Chelsea always had men attacking the far post when the ball was played back into the box from a corner, and there were no less than three doing so on this occasion (Rudiger, Morata, and Alonso all at the far post). Rudiger reacted well to the deflection on the shot to score what would be the winning goal.
Swansea’s strong defence provided a tough challenge for Chelsea to break down. They had numbers in the middle, didn’t allow Chelsea to change the speed of their attacks, and while they left space in wide areas, they compensated for that with numbers back and in position to clear crosses. It was a very one-sided game however as they were unable to keep the ball or win set pieces in Chelsea’s half.
Chelsea created (and failed to finish) better opportunities through crosses when Willian and Pedro moved to wider areas, making runs behind (along with Fabregas), and playing crosses to feet inside the box. The best opportunities were created through set pieces, where Chelsea consistently won the ball in the air; before a quick corner caught Swansea disorganised and led to the winning goal.
One of those days ... avoided.